Abstract
This paper presents a three-dimensional through-flow approach based on the cylindrical Euler equations incorporating a body force method. Blade performance is captured through a mixture of empirical correlations and a novel reverse flow treatment. The code is the first application of a physically correct Godunov solver to three-dimensional rotating stall and surge modelling. This solver ensures the accurate calculation of inter-cell fluxes unlike in typical modern CFD codes in which the non-linear convective terms are linearised. Validation consists of modelling a low speed three-stage axial compressor in all operating regions, recreating the reverse flow, rotating stall and forward flow characteristics with good agreement to experimental data. Additional comparisons are made against rotating stall cell size and speed, to which good agreement is also shown. The paper ends with some full surge cycle simulations modifying both the tank volume after the compressor and the level of inlet distortion applied. Both tank volume and level of distortion have been found to affect the type of instability developed. The development of this code is a step forward in compressor rotating stall and reverse flow modelling and allows recreation of a full compressor map at a significantly low computational cost when compared to commercially available 3D CFD codes.
Highlights
The operation of a jet engine is limited by the onset of compressor stall
The present paper proposes the application of a physically true solver to the already established methods of using body forces coupled with empirical correlations to model the post-stall behaviour of an axial compressor
The full map consists of the forward and reverse flow characteristics, with the forward flow characteristics formed of a rotating stall and pre-stall characteristic
Summary
The operation of a jet engine is limited by the onset of compressor stall. Rotating stall and surge are still not fully understood, neither in the mechanism through which the instability is triggered and subsequently develops, nor the aerodynamic load that is imposed on individual turbomachinery components during the event. This generally leads to a conservative approach during the design of blades and casings, and penalises the nominal operability range of the engine. Numerous solutions have been investigated to suppress the occurrence of compressor stall and increase surge margin. Imani and Montazeri-Gh [7] proposed an improvement on the Min–Max limit protection in the control of aero-engines to reduce the pos-
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