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Shock Wave Strength Reduction by Passive Control Using Perforated Plates

Journal of Thermal Science 2007年第2期16卷 97-104页

作者： Piotr Doerffer oskar szulc Institute of Fluid-Flow Machinery Polish Academy of SciencesFiszera 1480-952 GdaskPoland

Strong, normal shock wave, terminating a local supersonic area on an airfoil, not only limits aerodynamic performance but also becomes a source of a high-speed impulsive helicopter noise. The application of a passive control system （a cavity covered by a perforated plate） on a rotor blade should reduce the noise created by a moving shock. This article covers the numerical implementation of the Bohning/Doerffer transpiration law into the SPARC code and includes an extended validation against the experimental data for relatively simple geometries of transonic nozzles. It is a first step towards a full simulation of a helicopter rotor equipped with a noise reducing passive control device in hover and in forward flight conditions.

关键词： transonic flows shock wave - boundary layer interaction passive control.

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Shock Wave Smearing by Passive Control

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Journal of Thermal Science 2006年第1期15卷 43-47,42页

作者： Piotr DOERFFER oskar szulc Rainer BOHNING IMP PAN Fiszera 14 PL-80 952 Gdansk Poland ISL Universitat Karlsruhe Karlsruhe Germany

Normal shock wave, terminating a local supersonic area on an airfoil, limits its performance and becomes a source of high speed impulsive noise. It is proposed to use passive control to disintegrate the shock wave. Details of the flow structure obtained by this method are studied numerically. A new boundary condition has been developed and the results of its application are verified against experiments in a nozzle flow. The method of shock wave disintegration has been confirmed and detailed analysis of the flow details is presented. The substitution of a shock wave by a gradual compression changes completely the source of the high speed impulsive noise and bears potential of its reduction.

关键词： transonic flows shock wave boundary layer interaction passive control.

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维普期刊数据库

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Shock Wave-Boundary Layer Interaction in Forced Shock Oscillations

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Journal of Thermal Science 2003年第1期12卷 10-15页

作者： Piotr Doerffer oskar szulc Franco Magagnato Institute of Fluid-Flow Machinery Polish Academy of Sciences Fiszera 14Institute of Fluid-Flow Machinery Polish Academy of Sciences Fiszera 14Institute fur Stromungslehre Universitat Karlsruhe Kaiserstr. 12 80-952 Gdansk Poland 80-952 Gdansk Poland D-76128 Karlsruhe Germany

The flow in transonic diffusers as well as in supersonic air intakes becomes often unsteady due to shock wave boundary layer interaction. The oscillations may be induced by natural separation unsteadiness or may be forced by boundary conditions. Significant improvement of CFD tools, increase of computer resources as well as development of experimental methods have *** the attention of researchers to this topic. To investigate the problem forced oscillations of transonic turbulent flow in asymmetric two-dimensional Laval nozzle were considered. A viscous, perfect gas flow, was numerically simulated using the Reynolds-averaged compressible Navier-Stokes solver SPARC, employing a two-equation, eddy viscosity, turbulence closure in the URANS *** time-dependent and stationary flow simulations, Mach numbers upstream of the shock between 1.2 and 1.4 were considered. Comparison of computed and experimental data for steady states generally gave acceptable agreement. In the case of forced oscillations, a harmonic pressure variation was prescribed at the exit plane resulting in shock wave motion. Excitation frequencies between 0 Hz and 1024 Hz were investigated at the same pressure *** main result of the work carried out is the relation between the amplitude of the shock wave motion and the excitation frequency in the investigated range. Increasing excitation frequency resulted in decreasing amplitude of the shock movement. At high frequencies a natural mode of shock oscillation (of small amplitude) was observed which is not sensitive to forced excitement.

关键词： unsteady transonic flow shock wave nozzle flow.

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