Victor Kasyanov

Work: Supersonic jet noise and influence of instability waves on it. Central Aero-Hydrodynamics Institute.

Main results: There is a series of works directed to instability wave research for uniform non-symmetrical jets. But known methods are not efficient for generalization for the case of real non-uniform jets due to different reasons. Our work presents a new method of solving the spectral problem for linear disturbances in a uniform jet of arbitrary section shape. A case of thin mixing layer (flow with vortex sheet) is discussed. This problem corresponds to the very initial part of jet where instability waves originate. The method is based on presenting instability waves in the form of Fourier series with respect to azimuthal harmonics and on reducing the task to a system of algebraic equations. It seems that such an approach can be an effective basis for the noise prediction method relating to non-uniform supersonic jets of arbitrary section shape. Three tasks have been considered in the problem.

1. Two-dimensional instability waves of Kelvin-Helmholtz on a plane vortex sheet. The effect of flow Mach number and flow temperature on the increase rate of spatial instability waves is analyzed.
2. Instability waves on a circular jet with a thin mixing layer is considered.
3. Spectral problem for a jet of arbitrary section shape with a thin mixing layer (vortex sheet of arbitrary section shape) is investigated. The effect of jet section shape on eigen-wave numbers and instability wave shape are regarded.