Combustor Turbine Interface Studies—Part 1: Endwall Effectiveness Measurements

Abstract

Improved durability of gas turbine engines is an objective for both military and commercial aeroengines as well as for power generation engines. One region susceptible to degradation in an engine is the junction between the combustor and first vane given that the main gas path temperatures at this location are the highest. The platform at this junction is quite complex in that secondary flow effects, such as the leading edge vortex, are dominant. Past computational studies have shown that the total pressure profile exiting the combustor dictates the development of the secondary flows that are formed. This study examines the effect of varying the combustor liner film-cooling and junction slot flows on the adiabatic wall temperatures measured on the platform of the first vane. The experiments were performed using large-scale models of a combustor and nozzle guide vane in a wind tunnel facility. The results show that varying the coolant injection from the upstream combustor liner leads to differing total pressure profiles entering the turbine vane passage. Endwall adiabatic effectiveness measurements indicate that the coolant does not exit the upstream combustor slot uniformly, but instead accumulates along the suction side of the vane and endwall. Increasing the liner cooling continued to reduce endwall temperatures, which was not found to be true with increasing the film-cooling from the liner.

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.…”

Spontaneous rotational Raman thermometry for air flow characterization in a turbomachine test rig

“…The physics of combustor–turbine interaction is not yet fully understood. This interface is characterized by extreme phenomena such as hot gases, unstable boundary layers, turbulence effects, and inherent unsteadiness . Due to the complexity of the flow and the mechanical access restrictions, measurement is challenging.…”

Experimental Evaluation of an Inlet Profile Generator for High-Pressure Turbine Tests

“…Very little experimental data exists that documents total pressure profiles at the combustor exit. This information is paramount since it has been shown in Hermanson and Thole [15] and Colban et al [14] that the total pressure field is a driving force in the development of secondary flows and heat transfer present in the downstream turbine vane passages.…”

“…Figure 6 shows an example of a pressure profile at the exit of an aeroengine combustor, as well as three pressure profiles generated using the TRF simulator and two generated using the Virginia Tech simulator. The TRF simulator was designed using this engine profile and the Virginia Tech (VT) simulator profiles, documented in Barringer et al [5] and Colban et al [14]. Figure 6 also shows the pressure profile at the TRF turbine inlet prior to installing the simulator.…”

“…Colban et al [14] studied the effects of varying film cooling flow through the liner and exit junction slot in a largescale (9X), low speed combustor simulator on the adiabatic effectiveness and secondary flow development within a downstream turbine cascade. Results showed that varying the coolant injection through the liner led to different total pressure profiles entering the downstream turbine section.…”