The pressure waves produced by the convection of temperature disturbances in high subsonic nozzle flows

Abstract

The method of characteristics is used to calculate the unsteady one-dimensional flow produced by the convection of a temperature disturbance, contained between two contact surfaces, in high subsonic flow through a nozzle. The results show the development of the pressure disturbances which are associated with the force perturbation needed to accelerate the temperature disturbance at the same rate as the surrounding gas and propagate in both the upstream and downstream directions. Using a simple flow model, expressions for the mean pressure disturbances are derived and shown to be in good agreement with numerical solutions. Other numerical solutions which show the effect of changing the various flow parameters and the nozzle shape are presented. In all of the cases considered, the pressure disturbances caused by a 10 % change in the inlet temperature are significantly large and may be an important part of ‘excess’ noise.

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