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Fig. 2.61 The range of influence of disturbance sources with different speeds
(3) Sound velocity disturbance source (Ma = 1, v = a)
In the flow field where the disturbance source moves at the speed of
sound, the small disturbance will not be transmitted to the upstream
of the disturbance source, and the airflow does not feel any disturbance before the disturbance source arrives, so the existence of the
disturbance source is not known.
(4) Supersonic disturbance source (Ma > 1, V > a)
If the disturbance source moves at supersonic speed, the influence
range of a small disturbance will be smaller. When a small disturbance occurs to the supersonic flow, it will propagate around at the
speed of sound. The envelope surface of the disturbed spherical wave
is called the disturbed interface, which is also called the Mach wave
array surface, which is called the Mach wave for short. For the point
disturbance source, it is also called the Mach cone because of the
conical shape of the array (the shape of the Mach wave array with
different shapes is different, for example, the influence area of the thin
wedge-shaped object is wedge-shaped, for the slender cone-shaped