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Aerospace側風侧风，又称横风，是指与某一方向或行进方向有正交分量的风。 在航空中，侧风是指风的一部分吹过跑道，使得起飞降落较风向与跑道平行时更加困难的风。如果侧风足够强烈，并超过了飞机侧风限制，在此极限条件下试图降落有可能引发飞机起落架的结构性损伤。侧风有时也会缩写为X/WIND。 侧风在湿滑路面上行驶时也会造成麻烦，尤其是有瞬时强风，并且车辆侧面面积较大的时候。这对于驾驶员来说具有危险，因为可能产生升力，同时引发车辆方向改变。对于驾驶员来说，最安全的处理方法是降速，以降低升力，然后驶入侧风的方向。 当风向与驾驶方向不完全平行的时候，这种风被称作具有侧风分量，意思是这种风可以分成两个部分，一个侧风，和一个顺风/逆风分量。在这种条件下，车辆的表现与只遇到其侧风分量时相同。 侧风分量是由风与行进方向的夹角的正弦乘以风速，逆风分量与侧风分量计算方式相同，只是使用余弦而非正弦。在现实世界飞行的飞行员一般通过一个绘有风速与夹角的表格来阅读侧风分量的值。
A crosswind is any wind that has a perpendicular component to the line or direction of travel. This affects the aerodynamics of many forms of transport. Moving non-parallel to the wind direction creates a crosswind component on the object and thus increasing the apparent wind on the object; such use of cross wind travel is used to advantage by sailing craft, kiteboarding craft, power kiting, etc. On the other side, crosswind moves the path of vehicles sideways and can be a hazard.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 风扇，日本和韩国称为扇风机，风扇通过驱动扇叶旋转使空气加速流通，风扇中包括旋转的叶片，叶片材质有木头、塑胶或是金属，对空气作用，以产生气流。叶片和轮毂会合称叶轮或是转子。有时风扇会装在一外壳内。外壳可以导引气流，也避免其他物品接触到旋转中的扇叶，提升其安全性。目前大部分的风扇是由电动机驱动，因此也称电风扇或是电扇，不过也可以用其他的动力来源来驱动风扇，例如油压马达、曲柄及内燃机。 若以机械的观点来看，任何可以旋转产生气流的设备都是风扇。风扇可以产生大量的气流，压力较低（不过仍比外界压力要大），压缩机则和其相反，产生的气流压力很大，但流量较小。一般扇叶在气流底下会开始旋转，其他利用此性质的设备（像是风速计和风力发动机）也会设计成和风扇类似。 风扇常见的应用包括空调控制、维持个人的热舒适性（像是电子的桌扇及落地扇）、汽车引擎冷却系统（风扇会放在水箱散热器之前）、机器冷却系统（例如电脑内，或是音频功率放大器内）、通风、排烟、扬谷（分离谷壳和谷物）、除尘（例如吸尘器内）、干燥（一般会配合热源进行）。有些工业热交换器中会装风扇来间接冷却。 风扇对物体冷却的效果很好，但风扇不会直接降低空气温度，风扇可以让人凉爽，是因为汗水的蒸发冷却，并且因为风扇产生的气流，增加和周围空气的热对流。因此若周围空气温度很高，或是湿度很高，风扇冷却的效果就比较差。
A fan is a powered machine that creates airflow. A fan consists of rotating vanes or blades, generally made of wood, plastic, or metal, which act on the air. The rotating assembly of blades and hub is known as an impeller, rotor, or runner. Usually, it is contained within some form of housing, or case. This housing will allow air to pass through as well as directing the airflow, or increasing safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors, handcranks, and internal combustion engines. Mechanically, a fan can be any revolving vane, or vanes used for producing currents of air. Fans produce air flows with high volume and low pressure (although higher than ambient pressure), as opposed to compressors which produce high pressures at a comparatively low volume. A fan blade will often rotate when exposed to an air-fluid stream, and devices that take advantage of this, such as anemometers and wind turbines, often have designs similar to that of a fan.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 流体动力学（英语：Fluid dynamics）是流体力学的一门子学科。流体动力学研究的对象是运动中的流体（含液体和气体）的状态与规律。流体动力学底下的子学科包括有空气动力学和液体动力学。 解决一个典型的流体动力学问题，需要计算流体的多项特性，主要包括速度、压力、密度、温度。 流体动力学有很大的应用，比如在预测天气，计算飞机所受的力和力矩，输油管线中石油的流率等方面上。其中的一些原理甚至运用在运输工程，因交通运输本身可被视为一连续流体运动。
In physics, physical chemistry, and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including aerodynamics (the study of air and other gases in motion) and hydrodynamics (the study of water and other liquids in motion). Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the mass flow rate of petroleum through pipelines, predicting weather patterns, understanding nebulae in interstellar space, understanding large scale geophysical flows involving oceans/atmosphere and modelling fission weapon detonation. Fluid dynamics offers a systematic structure—which underlies these practical disciplines—that embraces empirical and semi-empirical laws derived from flow measurement and used to solve practical problems. The solution to a fluid dynamics problem typically involves the calculation of various properties of the fluid, such as flow velocity, pressure, density, and temperature, as functions of space and time.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 地面效应（Wing-In-Ground effect, WIG）亦称为地面效应（Ground effect）或翼面效应（Wing-In-Surface-Effect, WISE），是一种使飞行器诱导阻力减小，同时能获得比空中飞行更高升阻比的流体力学效应：当运动的飞行器距离地面（或水面）很近时，整个飞行器体的上下压力差增大，升力会陡然增加。前苏联就是利用这种效应，研制多款翼地效应飞行器并进行实际的测试飞行。 这种现像在飞机或是赛车产生的气流被地面或水面影响时，就会发生。 此种现像主要使用在两个地方： 赛车利用特殊设计的车底来产生下压力，以增加轮胎的正向力，进而提升抓地力表现。 地面效应机（Wing-In-Ground Vehicle, Ground Effect Vehicle GEV）是一种利用地面效应所产生的强大上扬力来飞行的特殊航空器。
In aircraft, the ground effect is the reduced aerodynamic drag that an aircraft's wings generate when they are close to a surface (land or water). The principal benefit of operating in ground effect is to reduce its lift-induced drag. The closer the wing operates to a surface such as the ground ("in ground effect"), the less drag it experiences. When an aircraft enters ground effect, the surface pushes back against the downwash, which reduces its drag. During takeoff, ground effect can cause an aircraft to "float" while accelerating towards the climb speed, reducing friction.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 飞、飞翔或飞行是物体的一种行进方式。方法有许多种，例如利用与空气动力学原理产生升力（如飞机或鸟类）；也可以经由比空气更轻的重量来达成目的（如热气球）；还有一种飞行方式并不在空气当中，而是在太空里，称为太空飞行。在虚构作品中，也有人假想能利用魔法或超自然力量、超能力来飞。
Flight or flying is the motion of an object through an atmosphere or through the vacuum of space, in this case also called spaceflight, without contacting any planetary surface. This can be achieved by generating aerodynamic lift associated with gliding or propulsive thrust, aerostatically using buoyancy, or by ballistic movement. Many things can fly, from animal aviators such as birds, bats and insects, to natural gliders/parachuters such as patagial animals, anemochorous seeds and ballistospores, to human inventions like aircraft (airplanes, helicopters, airships, balloons, etc.) and rockets which may propel spacecraft and spaceplanes. The engineering aspects of flight are the purview of aerospace engineering. It has three subfields: aeronautics — the study of vehicles that travel through the atmosphere. astronautics — the study of vehicles that travel through space. ballistics — the study of the flight of projectiles.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 亥姆霍兹定理（英语：Helmholtz's theorems）是流体力学中关于涡旋动力学性质的三条定理，以德国物理学家赫尔曼·冯·亥姆霍兹的名字命名。 亥姆霍兹定理适用于有势体积力作用下的无粘性、正压流体，其表述分别为： 亥姆霍兹第一定理：涡线的强度沿涡线保持不变。 亥姆霍兹第二定理：涡线在流体中不会自行产生或消失，只能首尾相接、沿伸至无穷远处或终止于边界处。 亥姆霍兹第三定理：无外力影响下，无旋流动始终保持无旋。
In fluid mechanics, Helmholtz's theorems, named after Hermann von Helmholtz, describe the three-dimensional motion of fluid in the vicinity of vortex lines. These theorems apply to inviscid flows and flows where the influence of viscous forces are small and can be ignored. Helmholtz's three theorems are as follows: Helmholtz's first theorem The strength of a vortex line is constant along its length. Helmholtz's second theorem A vortex line cannot end in a fluid; it must extend to the boundaries of the fluid or form a closed path. Helmholtz's third theorem A fluid element that is initially irrotational remains irrotational. Helmholtz's theorems apply to inviscid flows. In observations of vortices in real fluids the strength of the vortices always decays gradually due to the dissipative effect of viscous forces. Alternative expressions of the three theorems are as follows: The strength of a vortex tube does not vary with time. Fluid elements lying on a vortex line at some instant continue to lie on that vortex line. More simply, vortex lines move with the fluid.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 高超音速飞行(英文：Hypersonic flight)是指以高于5马赫的速度通过大约90公里以下的大气层飞行，这种速度下空气的解离开始变得显著并且存在高热应力。该技术亦应用在高超音速武器上，俄罗斯在2019年宣布成为世界首个部署高超音速武器的国家，并在2022年俄乌战争上首次实战使用该种武器。
Hypersonic flight refers to the motion of aircraft, missiles, or spacecraft through the atmosphere below the Karman line at speeds greater than Mach 5, above which thermochemical effects and aerodynamic heat loads become significant.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 普朗特-格劳尔奇点（英语：Prandtl–Glauert singularity，简称P.G. singularity）有时被称为锥状云、冲击领或冲击鞘。 当航空器以突破音速的高速巡航时，前端会短暂出现锥形的冷凝云。一般认为气压突然下降是造成这种现象的主因，但由于机制未完全明朗，因此这种现象是空气动力学上的一个奇点。 航天飞机发射25秒至33秒之后，速度超过音速，即可见冷凝云出现在前缘。一些核子试爆的档案影片也记录了这种效应，1946年美国十字路行动进行水下试爆，核爆所产生的冲击波前端形成了短暂的冷凝雾云。这种云被称为“威尔逊云”，因为看起来与威尔逊云室中的现象类似。现代超高旁通比喷射引擎的扇叶，在起飞全速运转时也可见这种效应。 高速冲击之下的空气可被视为是处于绝热过程之下的，因此压力变化会引发空气温度的改变。在潮湿的空气里，冲击波中空气最稀薄的部分（贴近航空器的区域）温度会降至露点以下，使得空气中的水分快速凝结，形成可见的雾锥。压力的改变离航空器越远越小，因此凝结现象只会出现在航空器的前端周遭，并呈锥状。
The Prandtl–Glauert singularity is a theoretical construct in flow physics, often incorrectly used to explain vapor cones in transonic flows. It is the prediction by the Prandtl–Glauert transformation that infinite pressures would be experienced by an aircraft as it approaches the speed of sound. Because it is invalid to apply the transformation at these speeds, the predicted singularity does not emerge. The incorrect association is related to the early-20th-century misconception of the impenetrability of the sound barrier.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 起伏运动，或称周期运动。在这种状态下飞机的机首会因为空气阻力的关系自然地开始上扬导致飞机爬升，直到角度过大之后因为推力不足速度逐渐降低，最后导致机翼升力不足接近失速，机首突然剧烈地向下开始俯冲，并在俯冲的过程中增加空速；直到速度增加到一个程度机翼能够产生足够的上浮力之后，才有办法将下坠的飞机拉回，并开始进入下一次的上扬爬升阶段，重复循环。通常发生在液压系统损坏，导致各翼面的控制功能失效时发生。
In aviation, a phugoid or fugoid ( ) is an aircraft motion in which the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "downhill" and "uphill". This is one of the basic flight dynamics modes of an aircraft (others include short period, roll subsidence, dutch roll, and spiral divergence).
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 斜激波（英语：oblique shock）是指相对于来流方向倾斜的激波，与正激波相对。超音速流绕角转向并压缩时会产生斜激波。来流流线经激波后转过的角度相同。制造斜激波常见的方法之一是在超音速流中放置楔形物。与正激波相似，气体热力学性质在穿过非常薄的斜激波区域时有近似不连续的变化。但与正激波不同的是，正激波不会改变来流方向，而斜激波则会。 通过伽利略变换，可以将斜激波转化为正激波。
An oblique shock wave is a shock wave that, unlike a normal shock, is inclined with respect to the direction of incoming air. It occurs when a supersonic flow encounters a corner that effectively turns the flow into itself and compresses. The upstream streamlines are uniformly deflected after the shock wave. The most common way to produce an oblique shock wave is to place a wedge into supersonic, compressible flow. Similar to a normal shock wave, the oblique shock wave consists of a very thin region across which nearly discontinuous changes in the thermodynamic properties of a gas occur. While the upstream and downstream flow directions are unchanged across a normal shock, they are different for flow across an oblique shock wave. It is always possible to convert an oblique shock into a normal shock by a Galilean transformation.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ NACA翼型是美国国家航空咨询委员会（NACA）开发的一系列翼型。每个翼型的代号由“NACA”这四个字母与一串数字组成，将这串数字所描述的几何参数代入特定方程中即可得到翼型的精确形状。
The NACA airfoil series is a set of standardized airfoil shapes, developed by NACA, which became widely used in the design of aircraft wings.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 普朗特－迈耶膨胀扇（英语：Prandtl–Meyer expansion fan）是指超音速流绕外凸转角时所形成的膨胀扇。膨胀扇由无穷多条从尖锐转角发散、角度逐渐偏转的马赫波组成。而当转角为光滑圆角时，这一系列马赫波则反向交汇于一点。物理上，绕凸角的超音速流不可能仅穿过一条“激波”，因为那样会违背热力学第二定律。当流动穿过膨胀扇时，流速与马赫数增加，静压、温度与密度则减小。由于该过程为等熵过程，滞止性质则保持不变。
A Prandtl-Meyer expansion fan is a two-dimensional simple wave that occurs when a supersonic flow turns around a sharp convex corner. The fan consists of an infinite number of Mach waves, diverging from a sharp corner. Prandtl-Meyer expansions are a subset of centered waves, where all the Mach waves can be extended to meet at a point, regardless of whether that point is along the wall. Each wave in the expansion fan turns the flow gradually (in small steps). It is physically impossible for the flow to turn through a single "shock" wave because this would violate the second law of thermodynamics. Across the expansion fan, the flow accelerates (velocity increases) and the Mach number increases, while the static pressure, temperature and density decrease. Since the process is isentropic, the stagnation properties (e.g. the total pressure and total temperature) remain constant across the fan. The theory was described by Theodor Meyer on his thesis dissertation in 1908, along with his advisor Ludwig Prandtl, who had already discussed the problem a year before.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 最小操纵速度（VMC）是多引擎飞机（多发）的一种V速度。指的是当一台或多台发动机失效后，飞机仍能维持航向或横向操纵的最小校准空速。低于该速度时，飞行员将无法继续有效控制飞机。 最小操纵速度仅适用于至少仍有一台发动机工作的情况，其数值会随飞行阶段而变化。在着陆、空中飞行和地面滑行等不同阶段，VMC的数值各不相同，需要分别计算。而对于四发及以上飞机，还会存在更多不同类型的VMC。这些数据都会列入多发飞机的飞机飞行手册中。 在设计飞机垂直尾翼和飞行操纵面尺寸时，工程师也必须考虑这些设计对飞机最小操纵速度的影响。其速度通常通过飞行测试确定，是飞机适航认证过程的一部分。这些速度数据为飞行员安全操作飞机提供了重要依据。
The minimum control speed (VMC) of a multi-engine aircraft (specifically an airplane) is a V-speed that specifies the calibrated airspeed below which directional or lateral control of the aircraft can no longer be maintained, after the failure of one or more engines. The VMC only applies if at least one engine is still operative, and will depend on the stage of flight. Indeed, multiple VMCs have to be calculated for landing, air travel, and ground travel, and there are more still for aircraft with four or more engines. These are all included in the aircraft flight manual of all multi-engine aircraft. When design engineers are sizing an airplane's vertical tail and flight control surfaces, they have to take into account the effect this will have on the airplane's minimum control speeds. Minimum control speeds are typically established by flight tests as part of an aircraft certification process. They provide a guide to the pilot in the safe operation of the aircraft.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 标准温度与压力（英语：standard temperature and pressure，简称STP），或称标准状况，是一组用于实验测量的标准化环境设定，目的在于让不同数据间具有可比性。目前最常采用的标准来自国际纯化学和应用化学联合会（IUPAC）与国家标准技术研究所（NIST），但这些标准尚未获得全球一致认可。其他机构也各自制定了不同的标准定义。 在工业与商业应用中，标准温压条件对于气体与液体体积的表示，以及相关数据如体积流率的表达，至关重要，因为气体体积会随温度与压力而显著变化。例如常见的单位包括：标准立方米每秒（Sm³/s）与常态立方米每秒（Nm³/s）。 许多技术性出版物（如书籍、学术期刊、机械设备广告）常简略地标示“标准状况”，而未明确说明其实际定义；有时甚至以旧用语“常态条件”（normal conditions，简称NC）取代。这样的模糊用法在某些情况下容易引发误解与错误。较为严谨的做法，是明确标示所采用的温压参考条件。若未特别说明，则通常预设为近似室温环境：约1个大气压、273.15 K（0°C）、以及0%的相对湿度。
Standard temperature and pressure (STP), or standard conditions for temperature and pressure, are various standard sets of conditions for experimental measurements used to allow comparisons to be made between different sets of data. The most used standards are those of the International Union of Pure and Applied Chemistry (IUPAC) and the National Institute of Standards and Technology (NIST), although these are not universally accepted. Other organizations have established a variety of other definitions. In industry and commerce, the standard conditions for temperature and pressure are often necessary for expressing the volumes of gases and liquids and related quantities such as the rate of volumetric flow (the volumes of gases vary significantly with temperature and pressure): standard cubic meters per second (Sm3/s), and normal cubic meters per second (Nm3/s). Many technical publications (books, journals, advertisements for equipment and machinery) simply state "standard conditions" without specifying them, often substituting the term with older "normal conditions", or "NC".
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View content license ↗ 超声速（英语：supersonic）或超音速，是指超过环境中声速的速度。在海平面高度，气温摄氏20 °C（68 °F）空气中，声速大约是343米／秒（约等于1,125英尺／秒、768英里／小时或1,235千米／小时）。声速基本单位定义为1马赫（Mach），因此，超声速常以声速倍数——马赫数为量度单位。 声音是在弹性介质中行进的振动（压力波）。在气体中，声波是一种纵波，以不同速度行进，其中最相关的影响因素是气体的分子量与温度（气体压力影响较小）。既然气体温度与组成随着海拔改变甚钜，飞行器的马赫数可以在空速未有改变下有所变动。在室温的水中，速度超过1,440 m/s（4,700 ft/s）可被视为超声速。在固体中，声波可以是纵波或横波，而且传播速度更快。另外，如果观察者以超声速去追过去发出的声音，会发生声音倒带的现象。 物体只有一些部分（例如转子叶片的末梢）其周遭空气超过声速的情形，则称为跨声速（transonic）；出现这种情况，常见的物体速度值是介于0.8马赫与1.2马赫之间，单位换算如Mach 1（761 mph；1,225 km/h）。
Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately 343.2 m/s (1,126 ft/s; 768 mph; 667.1 kn; 1,236 km/h). Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic. Flights during which only some parts of the air surrounding an object, such as the ends of rotor blades, reach supersonic speeds are called transonic. This occurs typically somewhere between Mach 0.8 and Mach 1.2. Sounds are traveling vibrations in the form of pressure waves in an elastic medium. Objects move at supersonic speed when the objects move faster than the speed at which sound propagates through the medium. In gases, sound travels longitudinally at different speeds, mostly depending on the molecular mass and temperature of the gas, and pressure has little effect. Since air temperature and composition varies significantly with altitude, the speed of sound, and Mach numbers for a steadily moving object may change.
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View content license ↗ 声速（英语：Speed of sound），指声波在介质中传递的速率，定义为声波在单位时间内所行进的路径长。
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.92 s or one mile in 4.69 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0 °C (32 °F), the speed of sound in dry air (sea level 14.7 psi) is about 331 m/s (1,086 ft/s; 1,192 km/h; 740 mph; 643 kn). The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in dry air, deviating slightly from ideal behavior. In colloquial speech, speed of sound refers to the speed of sound waves in air. The speed of sound varies from substance to substance, however: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids.
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View content license ↗ 后掠翼是机翼设计的一种型态，特指机翼沿着翼展方向的轴线与机身具有一个向后的角度，即掠角为锐角。机翼的后掠程度由后掠角大小来进行表示。 后掠翼是平直机翼发展而来的，适用于较高的飞行速度，气动特点为可增大机翼的临界速度，并减小超音速飞行时的阻力。 后掠翼的理论最初由德国人在1930年代提出，第二次世界大战期间，使用后掠翼设计的飞机开始出现，包括德国的Me 262战斗机和Me 163战斗机。但是Me 262使用后掠翼的原意并非针对高速飞行下的控制。 第二次世界大战之后，随着飞行速度的提高，后掠翼和其他适合高速飞行的机翼同时受到广泛的注意，但是随着使用经验的累积，后掠翼逐渐成为1950到1960年代很常见的设计之一。 后掠翼不仅使用于军用飞机，巡航速度在亚音速范围的民航机也大量采用这种设计，以取得速度与航程之间的最佳效益。
A swept wing is a wing angled either backward or occasionally forward from its root rather than perpendicular to the fuselage. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigated in Germany as early as 1935 by Albert Betz and Adolph Busemann, finding application just before the end of the Second World War. It has the effect of delaying the shock waves and accompanying aerodynamic drag rise caused by fluid compressibility near the speed of sound, improving performance. Swept wings are therefore almost always used on jet aircraft designed to fly at these speeds. The term "swept wing" is normally used to mean "swept back", but variants include forward sweep, variable sweep wings and oblique wings in which one side sweeps forward and the other back. The delta wing is also aerodynamically a form of swept wing.
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View content license ↗ 静压（Static pressure）是流体力学名词，在伯努利定律中表示为“静压 + 动压 = 总压”。因为流体在任何一点的压强量测是量测到静压值，因此一般会省略静（static）一词。 在航空器的设计和运作中，静压是指航空器全静压系统里的气压。
In fluid mechanics the term static pressure refers to a term in Bernoulli's equation written as static pressure + dynamic pressure = total pressure. Since pressure measurements at any single point in a fluid always give the static pressure value, the 'static' is often dropped. In the design and operation of aircraft, static pressure is the air pressure in the aircraft's static pressure system.
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View content license ↗ 湍流（英语：Turbulent flow），在流体动力学中，是一种流体运动，其特征是压力和流速的无序变化。它与层流相对。 湍流十分常见，例如海浪、湍急的河流、滚滚的暴风云或烟囱冒出的烟雾，自然界中发生或工程应用中产生的大多数流体流动都是湍流。 湍流是由流体流动部分中的过度动能引起的，它克服了流体黏度的阻尼效应。出于这个原因，湍流通常在低黏度流体中实现。一般而言，在湍流中，会出现大小不一的非定常涡流，它们相互影响，因此由于摩擦效应而产生的阻力增加。这增加了通过管道泵送流体所需的能量。 湍流的开始可以通过无量纲雷诺数预测，即流体流动中动能与粘性阻尼的比率。然而，湍流长期以来一直难以详细地物理分析，湍流内部的相互作用会产生非常复杂的现象。理查德·费曼将湍流描述为经典物理学中最重要的未解决问题。 湍流在许多领域都有研究，如航空、空污、降水、气候变化。
In fluid dynamics, turbulence or turbulent flow is fluid motion exhibiting chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers. Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney, and most fluid flows occurring in nature or created in engineering applications are turbulent. Turbulence is caused by excessive kinetic energy in parts of a fluid flow, which overcomes the damping effect of the fluid's viscosity. For this reason, turbulence is commonly realized in low viscosity fluids. In general terms, in turbulent flow, unsteady vortices appear of many sizes which interact with each other, consequently drag due to friction effects increases. The onset of turbulence can be predicted by the dimensionless Reynolds number, the ratio of kinetic energy to viscous damping in a fluid flow.
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View content license ↗ 流体动力学中，涡旋（vortex，复数形式：vortices或vortexes）是指流体顺着某个方向（例如环绕直线或曲线轴）运动时形成的区域。这样的运动模式又称涡流（vortical flow）。 涡旋是由被扰动的流体，例如液体、气体和等离子体形成的。涡旋的例子包含烟圈，船舶和桨尾流中的涡流，以及热带气旋、龙卷风和尘卷风周围的风。飞机的尾流中会形成涡旋，并且涡旋是木星大气层中相当明显的特征。 涡旋是湍流的主要组成部分。在不存在外力和任何大尺度旋转中，流体的黏性摩擦会将流动趋向非旋涡旋。这样的涡旋中，流体速度最快的地方是紧邻涡旋轴心的区域，并且速度随距离成反比。流体速度场的旋度，即涡量，在接近涡旋轴的部分极高，但在涡旋的其他区域趋近于0，并且压力在接近轴时明显下降。 涡旋形成后可以移动、沿伸、扭曲，并且和其他的涡旋以复杂的方式相互作用。移动的涡旋会带有角动量和线动量、能量和质量。在稳定流涡旋中，流线和迹线是封闭的。移动或变化中涡旋的流线和迹线经常形成螺线。
In fluid dynamics, a vortex (pl.: vortices or vortexes) is a region in a fluid in which the flow revolves around an axis line, which may be straight or curved. Vortices form in stirred fluids and may be observed in smoke rings, whirlpools in the wake of a boat, and in the winds surrounding a tropical cyclone, tornado, or dust devil. Vortices are a major component of turbulent flow. The distribution of velocity, vorticity (the curl of the flow velocity), as well as the concept of circulation are used to characterize vortices. In most vortices, the fluid flow velocity is greatest next to its axis and decreases in inverse proportion to the distance from the axis. In the absence of external forces, viscous friction within the fluid tends to organize the flow into a collection of irrotational vortices, possibly superimposed to larger-scale flows, including larger-scale vortices. Once formed vortices can move, stretch, twist, and interact in complex ways. A moving vortex carries some angular and linear momentum, energy, and mass, with it.
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View content license ↗ 乘波体（Waverider），是一种高超音速飞机的设计，提高其超音速升阻比，其用自己的飞行产生一个升力面的冲击波。
A waverider is a hypersonic aircraft design that improves its supersonic lift-to-drag ratio by using the shock waves being generated by its own flight as a lifting surface, a phenomenon known as compression lift. The waverider remains a well-studied design for high-speed aircraft in the Mach 5 and higher hypersonic regime, although no such design has yet entered production. The Boeing X-51 scramjet demonstration aircraft was tested from 2010 to 2013. In its final test flight, it reached a speed of Mach 5.1 (5,400 km/h; 3,400 mph).
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View content license ↗ 跨声速（transonic）或穿音速，是一个空气动力学名词，指的是一个正好在声速上下的速度范围（约0.8–1.2马赫）。其定义为临界马赫数（通常是0.8马赫附近）与一个更高速度（通常是1.2马赫）之间的速度范围，在这之间的速度范围，气流有些是超声速，也有些是亚音速。当飞行器速度超过临界马赫数，此时飞行器周遭的空气流开始有部分是超声速流，空气力学上开始出现急遽的变化，例如激波的出现；而当飞行器速度达1.2马赫时，此时所有气流皆为超声速，周遭气流变得稳定。 多数现代喷气飞机以可观的时间处在跨声速飞行。因为一个常出现在这样速度范围，称为波阻（wave drag）的效应而使这样的飞行状态显得重要。试图抵抗波阻效应的变革可在所有高速飞行器上见到；最显著的是后掠翼（swept wing）的设计，但另一个常见的形式是黄蜂腰形的机身（wasp-waist fuselage，亦称可乐瓶机身），作为Whitcomb面积律的副产品。
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2. The issue of transonic speed (or transonic region) first appeared during World War II. Pilots found as they approached the sound barrier the airflow caused aircraft to become unsteady. Experts found that shock waves can cause large-scale separation downstream, increasing drag, adding asymmetry and unsteadiness to the flow around the vehicle. Research has been done into weakening shock waves in transonic flight through the use of anti-shock bodies and supercritical airfoils. Most modern jet powered aircraft are engineered to operate at transonic air speeds. Transonic airspeeds see a rapid increase in drag from about Mach 0.8, and it is the fuel cost of the drag that typically limits the airspeed.
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View content license ↗ 涡环又称环形涡旋，是指流体中出现的环面状的涡旋。湍流中的液体和气体中经常出现涡环。例如蘑菇云和下击暴流中就存在涡环，烟圈就是一种涡环。另外有些大炮在发射时也会形成涡环。
A vortex ring, also called a toroidal vortex, is a torus-shaped vortex in a fluid; that is, a region where the fluid mostly spins around an imaginary axis line that forms a closed loop. The dominant flow in a vortex ring is said to be toroidal, more precisely poloidal. Vortex rings are plentiful in turbulent flows of liquids and gases, but are rarely noticed unless the motion of the fluid is revealed by suspended particles—as in the smoke rings which are often produced intentionally or accidentally by smokers. Fiery vortex rings are also a commonly produced trick by fire eaters. Visible vortex rings can also be formed by the firing of certain artillery, in mushroom clouds, in microbursts, and rarely in volcanic eruptions. A vortex ring usually tends to move in a direction that is perpendicular to the plane of the ring and such that the inner edge of the ring moves faster forward than the outer edge. Within a stationary body of fluid, a vortex ring can travel for relatively long distance, carrying the spinning fluid with it.
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View content license ↗ 垂直风洞（英语：Vertical wind tunnel）是一种将气流以垂直方式流动的风洞。它是一种娱乐用风洞，通常被称为室内跳伞（indoor skydiving）或是人体飞行（bodyflight）。它也常被使用在跳伞的训练上。 垂直风洞主要的功能，是让人类在不借助飞行伞、滑翔翼等等飞行器具的状况下，借由垂直产生的气流在空气中飘浮飞行。向上吹送的气流时速约为195公里/小时（120英里 或 55米/每秒），这是由人类在腹部朝下时的估算出的终端速度。它被称为室内跳伞的原因，是因为它的飞行模式带给人的感觉，十分近似真正的空中跳伞。
A vertical wind tunnel (VWT) is a wind tunnel that moves air up in a vertical column. Unlike standard wind tunnels, which have test sections that are oriented horizontally, as experienced in level flight, a vertical orientation enables gravity to be countered by drag instead of lift, as experienced in an aircraft spin or by a skydiver at terminal velocity. Although vertical wind tunnels have been built for aerodynamic research, the most high-profile are those used as recreational wind tunnels, frequently advertised as indoor skydiving or bodyflight, which have also become a popular training tool for skydivers.
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View content license ↗ 黏度（英语：viscosity）即“流体黏稠的程度”，是度量流体黏滞性大小的物理量。当液体、拟液体或拟固体物质受到外部剪切力作用时，发生形变与流动，分子间会产生内摩擦或流动内阻力，表征此相应的抗形变、抗流动特性的物理量，就是黏度。黏度的科学定义是力乘以时间除以面积。因此，其国际单位制为牛顿秒每平方米，或帕斯卡秒。 黏度也称动力黏度、黏（滞）性系数、内摩擦系数。不同物质的黏度不同，例如在室温（25℃）及常压（1巴）下，空气的黏度为18.5 μPa·s，大约是在相同温度下的水黏度的1/50。在常温（20℃）常压下，汽油的黏度为0.65 mPa·s，水为1 mPa·s，血液（37℃）为4～15 mPa·s，橄榄油为102 mPa·s，蓖麻油为103 mPa·s，蜂蜜为104 mPa·s，焦油为106 mPa·s，沥青为108 mPa·s等等。 黏滞力是流体受到剪应力变形或拉伸应力时所产生的阻力。在日常生活方面，黏滞像是“黏稠度”或“流体内的摩擦力”。因此，水是“稀薄”的，具有较低的黏滞力，而蜂蜜是“浓稠”的，具有较高的黏滞力。简单地说，黏滞力越低（黏滞系数低）的流体，流动性越佳。 黏滞力是黏性液体内部的一种流动阻力，并可能被认为是流体自身的摩擦。黏滞力主要来自分子间相互的吸引力。例如，高黏度酸性熔岩产生的火山通常为高而陡峭的锥状火山，因为其熔岩浓稠，在其冷却之前无法流至远距离因而不断向上累加；而黏滞力低的镁铁质熔岩将建立一个大规模、浅倾的盾状火山。所有真正的流体（除超流体）有一定的抗压力，因此有黏性。没有阻力对抗剪剪应力的流体被称为理想流体或无黏流体。 零黏度（对剪切应力没有抵抗力）仅在超流体的极低温度下观察到；否则，热力学第二定律要求所有流体都具有正黏度。具有零黏度（非黏性）的流体称为理想流体或无黏性流体。
In continuum mechanics, viscosity is a property of a fluid that quantifies the resistance force acting on fluids when there is relative motion between fluid parcels. This resistance force is caused by the stress in fluid parcels, which ideally is directly proportional to the strain rate (the time derivative of strain) that arises when fluid parcels are in relative motion, and the relative speed between the boundary between adjacent fluid parcels is zero. In liquids, viscosity arises from cohesive molecular forces, while in gases it results from molecular collisions. Except for the case of superfluidity, there is no fluid with zero viscosity, and thus all fluid flows involve viscous effects to some degree. For liquids, it corresponds to the informal concept of thickness; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 载人航天是指由宇航员执行的太空探索，可以由单人或多人执行，惟均需使用载人航天器进行。目前为止只有苏联及其继承国俄罗斯、美国、中华人民共和国三个国家有能力独立完成载人航天。 历史上首次载人航天任务是1961年4月12日苏联发射的东方1号，苏联宇航员尤里·加加林在环绕地球轨道一周后安全返回地球。5月5日，艾伦·谢泼德执行自由7号时成为了第一个进入太空的美国宇航员，也是人类历史上第二人，航天器在太空停留了15分钟。1963年6月16日，苏联宇航员瓦莲京娜·捷列什科娃执行东方6号任务时成为了第一名进入太空的女性。中国则是第三个尝试追赶美苏的国家，但载人计划在1973年被中途取消，直到三十年后的2003年，中国的航天员杨利伟乘坐神舟五号，成功围绕地球十四圈并安全返回地球，标志着中国成为第三个有能力独立完成载人航天的国家。目前除俄美中三国外，还有欧洲空间局、日本、印度、伊朗、马来西亚等国家和机构也在计划实施载人航天。 1966年，美国的双子星11号创造了最高地球轨道记录，飞行高度达1374公里。发射和修理哈勃太空望远镜的两次航天飞机任务也曾达到600公里左右的飞行高度。迄今为止，载人航天飞行目标在地球轨道之外的任务只限于月球，尽管月球本身也是地球的卫星。第一次去月球的载人任务阿波罗8号中，三位宇航员曾进入月球轨道。阿波罗10号第二次环绕了月球，在月球轨道进行了登月航天器的测试。阿波罗11号至17号中除了13号的六次任务都成功登月，每次都有两名宇航员踏上了月球。于是有十二名宇航员在执行阿波罗计划任务时完成了登月的壮举，并全部安全返回。 某些情况下，人类以外的动物也曾乘坐航天器进入太空，也曾有过多次没能返回地球的情况。狗是第一批进入太空的大型哺乳动物。 随着航天技术从学术及公用领域走入民间，载人航天也开始迈向商业化，并使包括太空旅游在内的商业太空飞行成为现实。
Human spaceflight (also referred to as crewed spaceflight, and historically as manned spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard crew. Spacecraft can also be remotely operated from ground stations on Earth, or autonomously, without any direct human involvement. People trained for spaceflight are called astronauts (American or other), cosmonauts (Russian), or taikonauts (Chinese); and non-professionals are referred to as spaceflight participants or spacefarers. Humans have had a continuous presence in space since 2 November 2000, on the International Space Station (ISS). The first human in space was Soviet cosmonaut Yuri Gagarin, who launched as part of the Soviet Union's Vostok program on 12 April 1961 at the beginning of the Space Race. On 5 May 1961, Alan Shepard became the first American in space, as part of Project Mercury. On 20 July 1969, American astronaut Neil Armstrong landed on the Moon and became the first human on an extraterrestrial body.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 翅膀亦称翼，为鸟与昆虫等动物用来飞行的器官。在现代，许多机械物件也会使用翅膀飞翔，例如航天飞机及飞机等。
A wing is a structure which produces both lift and drag while moving through air. Wings are defined by two shape characteristics, an airfoil section and a planform. Wing efficiency is expressed as lift-to-drag ratio, which compares the benefit of lift with the air resistance of a given wing shape, as it flies. Aerodynamics includes the study of wing performance in air. Equivalent foils that move through water are found on hydrofoil power vessels and foiling sailboats that lift out of the water at speed and on submarines that use diving planes to point the boat upwards or downwards, while running submerged. The study of foil performance in water is a subfield of Hydrodynamics.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 航天器（英语：spacecraft），又名太空载具、太空船或空天飞船，是在地球大气层以外的宇宙空间中，基本按照天体力学的规律运动的各种飞行器。航天活动中常见的航天器包括人造卫星、空间探测器、航天飞机和各种空间站等。除非使用设想中的单级入轨技术，否则目前所有航天器都无法自行进入空天，需要搭乘运载火箭（运载火箭本身一般不算航天器）。 亚轨道飞行是指航天器进入空天后返回地表，但并未获得足够的能量或速度完成一次完整的地球轨道飞行。轨道飞行是指航天器进入围绕地球或其他天体的闭合轨道。载人航天器在发射时或在轨时（空间站）搭载人员，而无人航天器则以自主或远程操控的方式运行。围绕地球运行的无人航天器称为人造卫星，其中用于空间站货运补给的称为货运航天器；用于地球轨道以外飞行的无人航天器称为深空探测器。围绕其他行星运行的无人航天器称为轨道器；在其他天体着陆的称为着陆器；着陆后能够在表面移动的称为巡视器。大部分航天器在太阳系内运行，迄今为止只有少数探测器，例如先驱者10号和11号、旅行者1号和2号以及新视野号，正在离开太阳系。 轨道航天器可分为可回收式和不可回收式两种。大多数航天器不可回收。可回收式航天器根据其返回地球的方式可分为无翼的飞船和有翼的航天飞机。可回收式航天器又可分为可重复使用式（可再次发射一次或多次，例如SpaceX的龙飞船和航天飞机轨道器）和一次性使用式（例如联盟号飞船）。 航天器要完成其任务必须具备发射场、运载器、航天测控系统、数据采集系统、用户站台以及回收设施等的配合。如果需要载人，更需要携带维生资源、生命保障系统、成员观察训练程序的协助。
A spacecraft is a vehicle that is designed to fly and operate in outer space. Spacecraft are used for a variety of purposes, including communications, Earth observation, meteorology, navigation, space colonization, planetary exploration, and transportation of humans and cargo. All spacecraft except single-stage-to-orbit vehicles cannot get into space on their own, and require a launch vehicle (carrier rocket). On a sub-orbital spaceflight, a space vehicle enters space and then returns to the surface without having gained sufficient energy or velocity to make a full Earth orbit. For orbital spaceflights, spacecraft enter closed orbits around the Earth or around other celestial bodies. Spacecraft used for human spaceflight carry people on board as crew or passengers from start or on orbit (space stations) only, whereas those used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft used to support scientific research are space probes. Robotic spacecraft that remain in orbit around a planetary body are artificial satellites.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 风洞（英语：Wind tunnel）是空气动力学的研究工具。风洞是一种产生人造气流的管道，用于研究空气流经物体所产生的气动效应。风洞除了主要应用于汽车、飞行器、导弹（尤其是巡航导弹、空对空导弹等）设计领域，也适用于建筑物、高速列车、船舰的空气阻力、耐热与抗压试验等。
A wind tunnel is "an apparatus for producing a controlled stream of air for conducting aerodynamic experiments". The experiment is conducted in the test section of the wind tunnel and a complete tunnel configuration includes air ducting to and from the test section and a device for keeping the air in motion, such as a fan. Wind tunnel uses include assessing the effects of air on an aircraft in flight or a ground vehicle moving on land, and measuring the effect of wind on buildings and bridges. Wind tunnel test sections range in size from less than a foot across, to over 100 feet (30 m), and with air speeds from a light breeze to hypersonic. The earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautical research, as part of the effort to develop heavier-than-air flying machines. The wind tunnel reversed the usual situation. Instead of the air standing still and an aircraft moving, an object would be held still and the air moved around it.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 航天（英语：Spaceflight），字面意思是“在太空航行”，是指由探测器、人造卫星等航天器在太空或地外天体等地球大气层以外的地方进行的各种活动，包括科学研究、技术应用与宇宙探索等。 按航天活动的地点划分，航天包括短暂进入太空的亚轨道飞行、环绕地球的运行、飞往月球的航行、飞往太阳系内其他行星及其卫星的航行（行星际航行）、星际航行（恒星际旅行、星系际航行）。按航天器与探索、开发和利用对象的关系或位置划分，航天飞行方式包括飞越（从天体近旁飞过）、绕飞（环绕天体飞行）、着陆（降落在天体上面）、返回（脱离天体、重返地球）。按航天活动的目的，执行军事任务（具有军事目的）的航天活动，称为军用航天（军事航天）；执行科学研究、经济开发、工业生产等民用任务（具有非军事目的）的航天活动，称为民用航天。按航天的直接经济效果，通常由政府主导，不以营利为目的的，称为公共航天；通常由企业主导的，执行商业合同任务（以营利为目的）的航天活动，称为商业航天，其中由民营企业执行的称为民营航天。按人类参与程度，有人乘坐航天器的航天活动，称为载人航天，参与者称为航天员；反之则称为无人航天（机器人航天）。 公共航天的主要目的包括太空探索、宇宙观测与军用航天（间谍卫星），商业航天的主要用途是卫星通讯与地球观测，也有近来兴起的太空旅游。围绕航天活动建立的航天产业，覆盖火箭发射、航天器制造、航天器运营与测控等多个领域。
Spaceflight (also space flight) is an application of astronautics to fly objects, usually spacecraft, into or through outer space, either with or without humans on board. Most spaceflight is uncrewed and conducted mainly with spacecraft such as satellites in orbit around Earth, but also includes space probes for flights beyond Earth orbit. Such spaceflights operate either by telerobotic or autonomous control. The first spaceflights began in the 1950s with the launches of the Soviet Sputnik satellites and American Explorer and Vanguard missions. Human spaceflight programs include the Soyuz, Shenzhou, the past Apollo Moon landing and the Space Shuttle programs. Other current spaceflight are conducted to the International Space Station and to China's Tiangong Space Station. Spaceflights include the launches of Earth observation and telecommunications satellites, interplanetary missions, the rendezvouses and dockings with space stations, and crewed spaceflights on scientific or tourist missions.
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Wikipedia contributors · Retrieved2026-10-04 · CC BY-SA 4.0. Introductions were extracted as plain text and shortened. Language versions may emphasize different aspects.For concept reference; consult the original standards for authoritative requirements.
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