Large Eddy Simulation of a Controlled Diffusion Compressor Cascade

Abstract

In this research a Controlled Diffusion (CD) compressor cascade stator blade is simulated at a Reynolds number of ∼ 700, 000, based on inflow velocity and chord length, using Large Eddy Simulation (LES). A wide range of flow inlet angles are computed, including conditions near the design angle, and at high negative and positive incidence. At all inlet angles the surface pressure distributions are well-predicted by the LES. Near the design angle the computed suction side boundary layer thickness agrees well with experimental data, whilst the pressure side boundary layer is poorly predicted due to the inability of LES to capture natural boundary layer transition on the present grid. A good estimation of the loss is computed near the design angle, whilst at both high positive and negative incidences the loss is less well predicted owing to discrepancies between the computed and experimental boundary layer thickness. At incidences above the design angle a laminar separation bubble forms near the leading edge of the suction surface, which undergoes a transition to turbulence. Similar behaviour is noted on the pressure surface at negative incidence. At high negative incidence contra-rotating vortex pairs are found to form around the leading edge inThe authors would like to thank Rolls-Royce plc and the UK Technology Strategy Board for the funding this work under the CFMS Core Programme (TP/L3001H). The simulations in this study were performed on HECToR, the UK National Supercomputing Facility, under the UKAAC-2 Framework, EPSRC grant number EP/F005954/1. response to an unsteady stagnation line across the span of the blade. Such structures are not apparent in time-averaged statistical data due to their highly-transient nature.

Investigation of Streamwise and Transverse Instabilities on Swept Cylinders and Implications for Turbine Blading

“…It is often assumed that streamwise vorticity of this kind is confined to concave pressure surfaces. Examples of streamwise vorticity appearing on the convex surfaces of blades [9] and circular cylinders [10] have been observed both experimentally and computationally. The authors have observed streamwise vorticity on suction surfaces, both experimentally [4] and computationally [9].…”

“…Examples of streamwise vorticity appearing on the convex surfaces of blades [9] and circular cylinders [10] have been observed both experimentally and computationally. The authors have observed streamwise vorticity on suction surfaces, both experimentally [4] and computationally [9]. In this paper, examples of streamwise and crossflow vorticity on [4] convex surfaces will be considered.…”

Organized Streamwise Vorticity on Convex Surfaces With Particular Reference to Turbine Blades

“…A theory giving expected spanwise wavelengths for a circular cylinder was developed by Kestin and Wood 9 in 1970. "Streaky structures" and streamwise vortices have been observed and predicted on flat plates 10 , on compressor blades 11,12 and on the convex surface of a supercritical airfoil, following an initial concave surface exhibiting Görtler vorticity 13 . In a study of plane shear layers, Lasheras et al 14 have concluded that these are unstable to three-dimensional perturbations in the upstream conditions.…”

Evaluation of RANS turbulence models in simulating the corner separation of a high-speed compressor cascade

“…With the enormous development in computer science, the large eddy simulation (LES) method has been used in compressor cascade flow simulation in recent years, utilizing a large amount of computer resources (Matsuura & Kato, 2007;McMullan & Page, 2011;Teramoto, 2005;Zaki, Wissink, Durbin, & Rodi, 2009). Modeling threedimensional corner separation requires the CFD code to be very robust.…”