Speed of Sound and Supersonic boom
SOUND SPEED
As is known, sound is caused by molecules that oscillate under the effect of pressure. Molecules that oscillate form a sound wave by forming compressed regions. That is, one wavelength is the length between two congested vertical columns. The speed of sound refers to the speed of this sound wave.
In short, the speed of sound is the speed of the disorder produced by energy as it travels between molecules. Sound is a longitudinal wave.
As is known, the general velocity formula is V (velocity) = x (displacement) / t (time). Finding the speed of sound is also related to this formula. C (sound velocity) instead of V, λ (wavelength) instead of x, and T (time to advance a wavelength) period instead of t are used.
C = λ / T
T.f = 1 Because of T = 1 / f
the formula of sound velocity is defined as c = λ .f
This formula is valid not only for sound waves, but also for all waves that have the same behavior. Based on this equation, it is misleading to think that when we increase the frequency, the speed of sound will also increase. Because when the frequency increases, the wavelength decreases. Thus, the speed of sound remains constant. We cannot change the speed of the sound coming out of the speaker when we turn the volume up as much as we want. Since we can only increase the amplitude of the sound, we can increase the intensity of the sound. A large amplitude sound wave and a small amplitude sound wave can have equal sound velocities.
The only way to increase the speed of sound is to change the properties of the environment in which the sound is spread. In other words, in order to change the speed of sound, we have to change the temperature and density of the air.
c = √(k.R.T)
In this formula, k is the specific heat ratio of the ideal gas and is a function of temperature. R is the gas constant for an ideal gas. According to this formula, the speed of sound is just a function of temperature. While the speed of sound at 20 degrees is 343 meters per second, its speed at 0 degrees drops to 331 meters per second.
MACH NUMBER
The Mach number is a dimensionless number. Dimensionless numbers are used for evaluation because they give ratios. Mach number gives information about the speed of sound. It provides information on whether the flow reaches the speed of sound, based on the speed of the sound in ambient conditions.
Ma = V/c
In this formula, c is the velocity of sound in the environment. V is the flow velocity of the flow. Ma = 1 means the stream is at the speed of sound. Ma 1 is supersonic velocities.
SONIC EXPLOSION AND SHOCK WAVES
If Ma = 1 or Ma> 1 we mentioned above, the speed of sound and speed of sound are exceeded. In this case, shock waves are generated and can create a sonic explosion in the air. For example, in airplanes, sound waves jammed in front of the aircraft cause sonic explosions.
It is possible to reach supersonic velocities and create sonic explosions by using different geometries to increase the speed of the flow.
The devastating effect of the great forces created by sonic explosions reaching long distances cannot be ignored.