Acoustic waves in gas flows with sound speed discontinuities

Pulsations of gas pressure and temperature in two 2D gaseous strips with discontinuities of the gas velocity and sound speed at the boundary between the strips are studied analytically for various Mach numbers and strip widths, sound speeds and gas average velocities. The pulsation modes and resonances are analyzed with the aim to determine factors affecting the flow stability. It is found that for the flow stability, the speed inside one gas strip should be linked to its speed inside another strip. There is some possibility to influence the resonances within one strip by tuning the average gas velocity within another, but the strip width must be also changed to provide such tuning. Also, the temperature pulsation magnitude near the edge of the strip can be reduced by a phase shift between pressure and temperature pulsations.