超音速飞机（Supersonic plane）

超音速飞机（Supersonic plane） 超音速飞机(Supersonic plane) "Sonic booms" can only occur in certain weather conditions, and the halo, which is made of water vapor, lasts only a few seconds. When the speed of the vehicle reaches the speed of sound (1193km/h), it cools the surrounding air and condenses the moisture in the air. But it's not always accompanied by a sonic boom, and it's not a shock wave when the sound barrier breaks through. The sound barrier is a term used throughout history (mainly during world war ii) to try to cross the sound of a sound flight. This theory has been widely realized since the 1950s with the widespread realization of transonic flight. When an object (usually an aircraft) is approaching the speed of sound, it will gradually catch up with its own sound waves. At this point, as a result of the fuselage of air compression cannot spread rapidly, will gradually in the windward side of the airplane and its nearby area accumulated domain, eventually forming the air pressure, temperature, velocity, density and other physical properties of a surface of discontinuity, Shock Wave (or Shock, Shock Wave). The formation of shock waves is typical of supersonic flight. The shock surface will increase the air resistance to the aircraft, which is known as the sound barrier because of the speed of the speed of sound. In addition, in the early design of aircraft, due to the understanding of transonic aerodynamic is less, so has repeatedly collapse or crashed out of control when the plane tried to go beyond the speed of sound of serious accidents, someone put this period problem in aircraft manufacturing industry is also referred to as the "sound barrier". In fact, the word "sound barrier" has a reputation for media hype and public misunderstanding, rather than more profound physical reality. The vehicle enters supersonic flight forming the shock wave surface, is the acoustic energy high concentration surface, so called the sound cone. The sound cone is a short, extremely intense sound (possibly beyond the ear) that is known as Sonic Boom or Sonic Boom. Intense sonic will not only damage on the surface buildings, also can give the aircraft itself impact across the part of the huge pressure, so countries generally prohibit supersonic aircraft in the residential area above the breakthrough of sound. Transonic flight often accompany in addition, an effect known as Prandtl Laue condensation off - grid cloud (Prandtl - Glauert condensation clouds), the show is centered on plane axis, from the front wing began spreading evenly around the cone of clouds. This is due to the reduction of pressure caused by air pressure at the rear of the shock wave, resulting in condensation of water vapor. When water vapor condenses into tiny droplets, the naked eye looks like a cloud. This low pressure band will quickly disappear as the distance from the fuselage increases. It is worth mentioning that prandtl Laue condensation off - grid cloud, not can only see in transonic flight, also not necessarily associated with shock wave, it merely represents the air compressibility. Under the right conditions, a plane that has not yet been close to the speed of sound can also produce a prandt-glauerde-condensation cloud around itself. The cause of sonic boom When we pass the airport near the supersonic plane, it's possible to hear two loud bangs, like a thunderbolt. You'll be surprised if you hear it for the first time! Thought it was the plane shooting in the air, or something went wrong. In fact, this is the so-called sonic boom (also known as sonic boom) in supersonic flight. Why, then, is sonic boom, and why only supersonic flight? To understand this, we can start with a common natural phenomenon: In calm waters, if threw a stone, the water immediately appear a circle of ripples spread around, across the water, namely we often say "a stone up. But if the water that is moving on the surface of the water is being stirred in the water, that's not the case, for example, when a speedboat is speeding through the water, We see that the water that it stirs is not going to go round and round, but from the front of the boat, it's going to be spread out in a wedge. At the same time, we can see that the front edge is dense and the wave is very large, and the rear wave is very small. This kind of wave is called a wedge wave. This wave goes along with the clippers, and the range is always within the wedge. Likewise, for the air, there is this phenomenon, if you give a disturbance to the air, the sound will be transmitted outward in the form of a wave like water, and that is the sound wave. The sound that we hear is the sound of sound waves coming through the ear to stimulate the eardrum. When a plane is flying supersonic in the air, a wedge or conical wave can be seen in the nose or in the protruding part of the plane, as it does in the water. This is the shock wave. When they propagate outward, they interfere and influence each other, and then they converge into an all-around front shock wave and a rear shock wave that follows the tail. This kind of wave can be compared with the above wedges, but with very different properties. The thickness of shock wave is very small, and the pressure, density and temperature of the air after the wave are suddenly raised, and the velocity drops immediately. When these two shock waves spread to any space and objects, all can feel this kind of intense change, reflected in the man's ears, the ear drum is a sudden change of air pressure, feeling is two a roar and thundering sound. The sound is called sonic boom. Sonic booms only occur when the plane is supersonic. When a plane is flying at supersonic speeds at certain altitudes, intense pressure changes due to shock waves. We heard a sonic boom. Would a pilot with the plane have the same feeling? The pilot would not have heard the noise, because the pilot was sitting in the cockpit, the pressure, the density, the temperature of the shock wave, the pilot was not feeling it. Even if the cockpit is not sealed. Because the pilot is always in front of the front shock wave, in front of the back shock wave, that is to say, he is in the condition of a temporary stable pressure, which is also inaudible. The strength of the sonic boom and the size of the impact on the ground are directly related to the height of the flight. Because the shock wave is the same as the water, the farther away, the weaker the wave. When the plane a supersonic flight, not only the ground of human and animal can heard a deafening noise, influence people's life and work, serious still can shatter glass, and even damage to unstable buildings, causing direct losses. As the flight height increases, the effect is weaker and weaker, and when more than a certain height, the ground will not be affected. history A U.S. navy photographer quickly captured a picture of a fighter jet producing a sonic boom as it broke through the sound barrier. Shangdeng bing Jonathan - Chandler (Jonathan Chandler) took this photo on the 27th of July, when A F/A - 18 F "hornet" fighter planes are flying over the Philippines the United States "Kitty hawk" aircraft carrier at sea. # # # # # # # # # # # # # # # # # # # # # When the speed of the aircraft is close to the speed of sound, there will be a strong resistance that causes the aircraft to produce a strong oscillation and attenuation. This phenomenon is commonly known as the Sound Barrier. When breaking the sound barrier, the airframe's compression of the air cannot be transmitted rapidly, and gradually accumulated in the windward side of the aircraft, forming the shock surface, and the acoustic energy is concentrated on the shock surface. When the energy reaches people's ears, it can be seen as a short, intense explosion known as Sonic Boom.