Flow Diagnosis and Optimization Based on Vorticity Dynamics for Transonic Compressor/Fan Rotor

Abstract

This paper presents two optimized rotors. The first rotor is as part of a 3-blade row optimization (IGV-rotor-stator) of a high-pressure compressor. It is based on modifying blade angles and advanced control of curvature of the airfoil camber line. The effects of these advanced blade techniques on the performance of the transonic 1.5-stage compressor were calculated using a 3D Navier-Stokes solver combined with a vortex/vorticity dynamics diagnosis method. The first optimized rotor produces a 3-blade row efficiency improvement over the baseline of 1.45% while also improving stall margin. The throttling range of the compressor is expanded largely because the shock in the rotor tip area is further downstream than that in the baseline case at the operating point. Additionally, optimizing the 3-blade row block while only adjusting the rotor geometry ensures good matching of flow angles allowing the compressor to have more range. The flow diagnostics of the rotor blade based on vortex/vorticity dynamics indicate that the boundary-layer separation behind the shock is verified by on-wall signatures of vorticity and skinfriction vector lines. In addition, azimuthal vorticity and boundary vorticity flux (BVF) are shown to be two vital flow parameters of compressor aerodynamic performance that directly relate to the improved performance of the optimized transonic compressor blade. A second rotor-only optimization is also presented for a 2.9 pressure ratio transonic fan. The objective function is the axial moment based on the BVF. An 88.5% efficiency rotor is produced.

Anisotropic Turbulent Kinetic Energy Budgets in Compressible Rectangular Jets

“…Chen et. al [25] demonstrated flow diagnostics of a transonic compressor rotor using boundary vorticity flux to capture on-wall signatures of vorticity and skin-friction vector line at RANS level. Boundary vorticity flux is another method of capturing flow turbulence characteristics.…”

Improved Supersonic Turbulent Flow Characteristics Using Non-Linear Eddy Viscosity Relation in RANS and HPC-Enabled LES

“…Some researchers have attempted to characterize the turbulence in a tip-leakage flow of a single blade using non-linear RANS and zonal LES, as shown by Monier et al [24]. While Chen et al [25,26] demonstrated the vorticity dynamics-based flow diagnosis for a 1.5 stage high-pressure compressor using RANS simulations to improve compressor aerodynamic performance, Wu and Porté-Agel [27] presented the atmospheric turbulence effects on wind turbine wakes using LES. While these studies employed LES, Siddappaji [28] demonstrated TKE is equal to viscous dissipation using momentum, vorticity, and entropy transport through RANS simulations in adiabatic process with an in-house analysis framework.…”