激波（shock wave）.docVIP

激波（shock wave） In 40s, the sound speed close to the piston aircraft flying speed reached more than 700 kilometers per hour dive. Almost reached the speed limit of this kind of aircraft. When approaching the speed of sound, the aircraft will undergo severe buffeting. And it became very unstable and almost impossible to operate. Sometimes the buffeting too violent will destroy the aircraft wing and tail structures such as the tragic consequences of the crash fell to the ground. This is the so-called sound barrier. As people become more aware of this phenomenon, it is the result of a shock wave (also called a shock wave) and a wave drag on a plane during transonic flight. In order to explain the problem of shock wave and wave resistance, we first study the physical essence of sound velocity and sound wave. When the object moves very fast in the air, the air shows that it has a compressible physical property. Sound is the sound source in the air vibration, so that the surrounding air has periodic changes in pressure and density, forming a sparse dense density of the wave, this wave is heard by the eardrum, you can hear the sound. This air dilatational wave propagating sound, is called sonic. Acoustic propagation in the air velocity is the speed of sound. Sonic speed, at sea level, is about 1227 kilometers per hour, or 341 meters per second. The aircraft also compresses the air in front of it to create dense waves. The density and the sound wave is essentially the same, but its frequency is not within the scope of human feeling. The degree to which air is compressed is related to the density of the air and the pressure applied to the air. The greater the density of air (at low altitude or sea level), for example, the harder it is to compress air and the less compressed it will be. The greater the pressure applied to the air, the greater the degree of air compression. But the density of the air corresponds to the speed of sound. The density is large, the speed of sound is