Experimental Investigation of Turbine Stator Well Rim Seal, Re-Ingestion and Interstage Seal Flows Using Gas Concentration Techniques and Displacement Measurements

Abstract

Gas turbine engine performance requires effective and reliable internal cooling over the duty cycle of the engine. Life predictions for rotating components subject to the main gas path temperatures are vital. This demands increased precision in the specification of the internal air system flows which provide turbine stator well cooling and sealing. This in turn requires detailed knowledge of the flow rates through rim seals and interstage labyrinth seals. Knowledge of seal movement and clearances at operating temperatures is of great importance when prescribing these flows. A test facility has been developed at the University of Sussex, incorporating a two stage turbine rated at 400 kW with an individual stage pressure ratio of 1.7:1. The mechanical design of the test facility allows internal cooling geometry to be rapidly reconfigured, while cooling flow rates of between 0.71 Cw, ENT (>nd 1.46 C^^ ENT, inay be set to allow ingress or egress dominated cavity flows. The main annulus and cavity conditions correspond to in cavity rotational Reynolds numbers of 1.71 x 10^< Reip<1.93 x 70*. Displacement sensors have been used to establish hot running seal clearances over a range of stator well flow conditions, allowing realistic flow rates to be calculated. Additionally, gas seeding techniques have been developed, where stator well and main annulus flow interactions are evaluated by measuring changes in gas concentration. Experiments have been performed which allow rim seal and re-ingestion flows to be quantified. It will be shown that this work develops the measurement of stator well cooling flows and provides data suitable for the validation of improved thermo-mechanical and CFD codes, beneficial to the engine design process.

Main Annulus Gas Path Interactions—Turbine Stator Well Heat Transfer

“…by judicious placement and geometry optimisation, is investigated using adiabatic solutions. The validation of the methodology is also established through the demonstration of the coupled CFD/FE method, by comparisons to the data which have been measured on the test rig at the University of Sussex [8]. The disc surface thermocouple measurements have allowed validation of the method for this application, now that the fully coupled CFD/FE analysis capability has been established, (at least for some flow conditions).…”

“…Figure 2. A brief overview is given here; full details can be found in Coren [7] and Eastwood et al [8].…”

“…Figures 5 and 6 provide an overview of the test section temperature and pressure instrumentation. More information on the instrumentation is available from Coren [7] and Eastwood [8]. During the course of the analysis of the first phase of the rig test programme it became apparent that it was not possible to reconcile some of the observations from the rig measurements with the predictions of the CFD models.…”

Particle Image Velocimetry Measurement and Computational Fluid Dynamic Simulations of the Unsteady Flow Within a Rotating Disk Cavity

“…b2^j (1) where £2 and b are the rotational speed and radius of the rotating disk, respectively. Figure 5 shows the comparison of numerical and experimental dimensionless time-average pressure in the outer casing behind the guide vane.…”

“…Too much sealing air resulted in inefficiency; too little can lead to disastrous consequences [1], It is recognized that the flow behavior of the rim seal cavities are characterized by complex flows due to interaction with the main annulus gas. Sealing air, which is sup plied to the disk cavities to prevent this ingestion of hot main annulus gas, directly affects the engine performance.…”