Subsonic non-steady-state gas flows in channels with inner cavities

A set of gasdynamic equations is given in the general form for matter with an arbitrary equation of state in the case when the entropy equation is used instead of the energy equation. In the ideal gas approximation in view of viscosity, a numerical investigation is performed of non-steady-state two-dimensional flows in a channel with a cavity. The calculation results have demonstrated that, given the flow velocity and the geometry of channel and cavity, pressure pulsations arise that are due to the departure of vortices from the cavity into the main flow. The values of the amplitude and frequency of pressure pulsations are determined. If measures are taken aimed at limiting the departure of vortices from the cavity, for example, a baffle is installed to restrict the interaction between the main flow and gas in the cavity, one can considerably increase the flow velocity in the channel, unaffected by the cavity. Such non-steady-state flows may be realized in MHD-generator channels, resonators of gas flow lasers, gas ducts for ventilation and gas transport systems, mufflers, whistles, etc.