Nonaxisymmetric Turbine End Wall Design: Part II—Experimental Validation

Abstract

The Durham Linear Cascade has been redesigned with the nonaxisymmetric profiled end wall described in the first part of this paper, with the aim of reducing the effects of secondary flow. The design intent was to reduce the passage vortex strength and to produce a more uniform exit flow angle profile in the radial direction with less overturning at the wall. The new end wall has been tested in the linear cascade and a comprehensive set of measurements taken. These include traverses of the flow field at a number of axial planes and surface static pressure distributions on the end wall. Detailed comparisons have been made with the CFD design predictions, and also for the results with a planar end wall. In this way an improved understanding of the effects of end wall profiling has been obtained. The experimental results generally agree with the design predictions, showing a reduction in the strength of the secondary flow at the exit and a more uniform flow angle profile. In a turbine stage these effects would be expected to improve the performance of any downstream blade row. There is also a reduction in the overall loss, which was not given by the CFD design predictions. Areas where there are discrepancies between the CFD calculations and measurement are likely to be due to the turbulence model used. Conclusions for how the three-dimensional linear design system should be used to define end wall geometries for improved turbine performance are presented. [S0889-504X(00)01002-3]

Optimization of Endwall Contours of a Turbine Blade Row Using an Adjoint Method

“…For the redesigned blade, the secondary kinetic energy has been significantly reduced, compared with that of the reference blade. Disagreements were reported between computed flow loss and experimental results [37,38]. Compared with the planar endwall, the computational secondary flow loss of contoured endwall is larger, whereas it is smaller in experiments.…”

Secondary Flow Loss Reduction in a Turbine Cascade with a Linearly Varied Height Streamwise Endwall Fence

“…Work done by Ingram [8], Rose et al [10], and Harvey et al [11] demonstrates that using CSKE as objective function for secondary flow loss reduction can be highly successful. Experimental investigations by Kawai [1] and Govardhan et al [3] (on streamwise endwall fences) and Hartland et al [12] (on endwall profiling) have shown that a successful design produces a reduction in CSKE and exit flow angle along with a reduction in total pressure loss.…”

Numerical investigation of the influence of non-axisymmetric hub contouring on the performance of a shrouded axial compressor stator

“…Non-axisymmetric or 3D endwall contouring, meaning the additional degree of freedom that results when the annulus line of a turbine or compressor is no longer regarded to be axisymmetric, is already well established as a design feature for axial flow turbines. A large number of both numerical and experimental investigations at different levels of complexity has been reported [1,5,6,7,10,20,21]. Today, turbines with non-axisymmetric endwalls are present in several certified turbofan engines.…”