Experimental Investigation of Vane Clocking in a One and One-Half Stage High Pressure Turbine

Abstract

Aerodynamic measurements were acquired on a modern single-stage, transonic, high-pressure turbine with the adjacent low-pressure turbine vane row (a typical civilian one and one-half stage turbine rig) to observe the effects of low-pressure turbine vane clocking on overall turbine performance. The turbine rig (loosely referred to in this paper as the stage) was operated at design corrected conditions using the Ohio State University Gas Turbine Laboratory Turbine Test Facility. The research program utilized uncooled hardware in which all three airfoils were heavily instrumented at multiple spans to develop a full clocking dataset. The low-pressure turbine vane row (LPTV) was clocked relative to the high-pressure turbine vane row (HPTV). Various methods were used to evaluate the influence of clocking on the aeroperformance (efficiency) and the aerodynamics (pressure loading) of the LPTV, including time-resolved and time-averaged measurements. A change in overall efficiency of approximately 2–3% due to clocking effects is demonstrated and could be observed using a variety of independent methods. Maximum efficiency is obtained when the time-average surface pressures are highest on the LPTV and the time-resolved surface pressure (both in the time domain and frequency domain) show the least amount of variation. The overall effect is obtained by integrating over the entire airfoil, as the three-dimensional (3D) effects on the LPTV surface are significant. This experimental data set validates several computational research efforts that suggested wake migration is the primary reason for the perceived effectiveness of vane clocking. The suggestion that wake migration is the dominate mechanism in generating the clocking effect is also consistent with anecdotal evidence that fully cooled engine rigs do not see a great deal of clocking effect. This is consistent since the additional disturbances induced by the cooling flows and∕or the combustor make it extremely difficult to find an alignment for the LPTV given the strong 3D nature of modern high-pressure turbine flows.

Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

“…According to the early work from [55], the efficiency is achieved when the segments of the first vane wake avenue, released by the rotor, impinge on the leading edge of the second vane. The basic reason for this result is that the low momentum fluid coming from the first stage, collapse in the boundary layer of the second vane and for this do not affect the passage (among others, [56][57][58]), studied in detail the clocking effects driven by the stator secondary flows in a two stage subsonic and transonic turbines.…”

Vane Clocking in a Three-Stage Compressor: Frequency Domain Data Analysis

“…The turbine stage maximum efficiency condition occurs when the wake from the upstream vane row is positioned such that it impinges on the leading edge of the downstream vane. The minimum efficiency condition, typically out of phase with the optimum configuration by half a passage, occurs when the wake convects through the middle of the downstream vane passage [9][10][11][12][13].…”

Clocking effect of outlet RGVs on hydrodynamic characteristics in a centrifugal pump with an inlet inducer by CFD method

“…They found that the noise generated by blade interaction could be effectively reduced by properly adjusting the circumferential position of the rotor in a compressor. Later on, the clocking effect is proved to greatly affect the performances and CONTACT Chen-Xing Jiang jiangchenxing@hrbeu.edu.cn unsteady aerodynamic dynamics, and many investigators tried to find the optimal clocking position to maximize the efficiency and get the best transient behaviors (Behr et al, 2006;Dieter et al, 2005;Haldeman et al, 2005;Saren et al, 1998). In recent years, some researchers are focusing on the clocking effect in more areas.…”