Developments in Hot-Streak Simulators for Turbine Testing

Abstract

The importance of understanding the impact of hot-streaks, and temperature distortion in general, on the high pressure turbine is widely appreciated, although it is still generally the case that turbines are designed for uniform inlet temperature—often the predicted peak gas temperature. This is because there is an insufficiency of reliable experimental data both from operating combustors and from rotating turbine experiments in which a combustor representative inlet temperature profile has accurately been simulated. There is increasing interest, therefore, in experiments that attempt to address this deficiency. Combustor (hot-streak) simulators have been implemented in six rotating turbine test facilities for the study of the effects on turbine life, heat transfer, aerodynamics, blade forcing, and efficiency. Three methods have been used to simulate the temperature profile: (a) the use of foreign gas to simulate the density gradients that arise due to temperature differences, (b) heat exchanger temperature distortion generators, and (c) cold gas injection temperature distortion generators. Since 2004 three significant new temperature distortion generators have been commissioned, and this points to the current interest in the field. The three new distortion generators are very different in design. The generator designs are reviewed, and the temperature profiles that were measured are compared in the context of the available data from combustors, which are also collected. A universally accepted terminology for referring to and quantifying temperature distortion in turbines has so far not developed, and this has led to a certain amount of confusion regarding definitions and terminology, both of which have proliferated. A simple means of comparing profiles is adopted in the paper and is a possible candidate for future use. New whole-field combustor measurements are presented, and the design of an advanced simulator, which has recently been commissioned to simulate both radial and circumferential temperature nonuniformity profiles in the QinetiQ/Oxford Isentropic Light Piston Turbine Test Facility, is presented.

Experimental and Numerical Investigation of Combustor-Turbine Interaction Using an Isothermal, Nonreacting Tracer

“…"Inlet profile generators" are then used to approximate the combustor exit flow supplied to the turbine rig. State-of-the-art work along these lines include, most recently, the work of Colban and co-workers [3,4], Barringer and co-workers [5,6], Povey and Qureshi [7,8], and Simone et al [9]. These past approaches have led to an improved understanding of the sensitivity of the turbine to the various inflow parameters separately, e.g., OTDF level.…”

Design of a Nonreacting Combustor Simulator With Swirl and Temperature Distortion With Experimental Validation

“…Povey and Qureshi [1] provided a comprehensive review of facilities which were adapted for use in hot-streak (ITD) studies. Among the earlier facilities discussed (The Warm Core Turbine Test Facility at the NASA Lewis Research Center [2], The Large Scale Rotating Rig at the United Technologies Research Center [3], and The Rotating Blow-Down Facility at MIT [4,5]) experimental studies focused on the introduction of ITD and the investigation of ITD migration through the UP stage.…”

Integrated Combustor Turbine Design for Improved Aerothermal Performance: Effect of Dilution Air Control

“…There is a big variety in the temperature ratios used in combustors depending on the design field of application. Compared to the study of Povey et al [13], this ratio is in the range observed in modem annular combustors used in aircraft engines. The peak temperature was approximately positioned at midspan and midpassage between the two stator blades.…”