Unsteady laminar gas flows in an annular nozzle

On the basis of the Navier–Stokes equations, a parametric study of the influence of various factors on the development of initial perturbations caused by starting an air-blown annular nozzle is performed for the laminar model of flow. Flow regimes are found in which the start perturbations accompanying the initiation of the nozzle do not attenuate but pass to a quasi-periodic mode. The frequency Fourier spectrum of pressure fluctuations at the center of the thrust wall and the value of the thrust of the nozzle are determined. Typical pulsed pressure signals obtained in the calculation model and detected in the experiments are presented.