Numerical simulations of supersonic jet flows

Shih-Chieh Lo, Purdue University

Abstract

Supersonic jet flows are studied using 3-D large eddy simulation (LES). The farfield noise generated by the jets is investigated by a computational aeroacoustics (CAA) methodology that couples the near field unsteady flow field data computed by 3-D LES with a surface integral acoustic method for noise prediction. Since the engines of modern advanced commercial airliners and most military aircraft can operate with jets that exhaust at supersonic speed, predicting supersonic jet noise accurately has become one of the keys to designing new low noise emission engines that are suitable for future more restrictive noise regulations. Traditional approaches used to predict supersonic jet noise are based on experiments and semi-empirical models. With the recent improvements in the processor speeds of computers, the application of direct numerical simulation (DNS) and LES has become more feasible. In order to accurately simulate jets at supersonic speeds using LES, a suitable shock capturing scheme is developed and tested. Characteristic filters are used due to their low numerical dissipation and because they are suitable for incorporation into the current solver. To test the performance of the characteristic filters, several 1-D and 2-D numerical experiments are presented. The results using the characteristic filters combined with the shock detectors are satisfactory in capturing shocks and resolving turbulent fluctuations. In 3-D, both perfectly expanded and underexpanded unheated jets are investigated with and without using characteristic filters. Comparisons of the jet mean flow, turbulent statistics, and jet aeroacoustics results with other numerical and experimental data of jets at similar flow conditions were done and reasonable agreement is observed.

Degree

Ph.D.

Advisors

Blaisdell, Purdue University.

Subject Area

Aerospace engineering

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