HP Vane Aerodynamics and Heat Transfer in the Presence of Aggressive Inlet Swirl

Abstract

Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over ±40 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NOx combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.

The Influence of Combustor Swirl on Pressure Losses and the Propagation of Coolant Flows at the Large Scale Turbine Rig (LSTR): Experimental and Numerical Investigation

“…The results show a significant impact on performance, almost equal to superimposed swirl. Qureshi et al [6] observed a great impact of swirl orientation and clocking on endwall heat transfer: both a significant increase or a slight decrease in Nusselt numbers can occur. They determine local divergence and convergence of wall streamlines and as a consequence, an accumulation or dissipation of boundary layer fluid to be responsible.…”

Effect of Tip Clearance on Flow Field and Heat Transfer Characteristics in a Large Meridional Expansion Turbine

“…It is feasible to predict the accuracy of numerical calculation through qualitative comparison [25]. Qureshi et al [14], from Oxford University, carried out aerodynamics and heat transfer experiments and predictions in the MT1 turbine blades, and the shape and working condition of the MT1 turbine are very similar to the S2 blade in this study. By comparing the numerical simulation data with this experimental data, a reasonable calculation accuracy can be obtained.…”

“…This ratio is not random, but is based on relevant research. In the study of Qureshi et al [14] and Ameni et al [16], specific studies of this ratio are given. Non-adiabatic heat transfer numerical simulation models usually use isothermal wall conditions, and the wall temperature depends on the heat transfer between the wall and the main flow.…”

“…The shear-stress transport (SST) k-ω turbulence model was used in the steady simulation. The model was validated by using the experimental data of Qureshi et al [14].…”

Parameterised Model of 2D Combustor Exit Flow Conditions for High-Pressure Turbine Simulations

“…Different authors have studied the isolated effects of inlet swirl (Giller et al [14], Qureshi et al [15], Schmid et al [16], Beard et al [17], Insinna et al [18], and Jacobi et al [19]), hot streaks (He et al [20], Basol et al [21], and Beard et al [22]) and elevated turbulence (van Fossen et al [23]). However, there are few data, and no unifying theory exists with respect to their combined effects.…”