Turbulence Levels are High at the Combustor-Turbine Interface

Abstract

Turbulence measurements are made in a novel gas turbine rig facility recently used to study combustor-turbine interactions in jet engines [1]. The rig is capable of numerous area traverses surrounding engine turbine nozzle guide vanes (NGVs). The rig is unique in that complete engine hardware of the annular combustion subsystem is used to simulate the upstream flow entering the turbine. The rig operates at cold, near-atmospheric conditions. The turbulence measurements include both the turbulence intensities and lengthscales and span an area over a single combustor sector. Axial measurement planes include locations both upstream and downstream of the real engine hardware NGVs. The upstream plane corresponds to a conventional combustor-turbine interface plane. In [1], pressure, velocity, and passive scalar mixing measurements were presented along with RANS CFD predictions. Here, in addition to the newly measured turbulence quantities, large-eddy simulations (LES) are performed for the complete, coupled combustor-turbine system. Good agreement between rig data and CFD is seen at the combustor-turbine interface, with LES yielding improved predictions over RANS. For the flow through the NGV passages, vortex visualizations of the simulated flowfields show significant differences to the classic, commonly accepted picture of Langston [2] and others [3]. The difference is attributed to the high turbulence levels created by the combustor. The impact of the limitations of the combustor-turbine rig on these findings is discussed.

Isothermal Combustor Prediffuser and Fuel Injector Feed Arm Design Optimization Using the prometheus Design System

“…At this stage it should be pointed out that this geometry represents a perspex rig constructed at Loughborough University, similar to that presented by Cha et al [33] and is representative of a combustion module for a large civil engine.…”

Combustor Dilution Hole Placement and Its Effect on the Turbine Inlet Flowfield

“…Each steady RANS turbulence model predicted different temperature profiles at the turbine inlet plane and underpredicted jet mixing as well as lateral spreading. Cha et al [5] noted that higher-fidelity modeling (largeeddy simulation) more accurately predicted the turbulence intensities found at the combustor-turbine interface in their experiment. Simply modeling the combustor and turbine together may not be enough to ensure accurate results; higher-fidelity unsteady models are needed to accurately predict the large turbulent structures stemming from the unsteady combustor flowfield.…”

“…These results vary with dilution jet arrangement, hole size, hole location, and momentum flux ratio. Cha et al [5] found turbulence levels at the combustor-turbine interface of approximately 35% and length scales of up to 25% of the vane chord length. Vakil and Thole [6] used a nonreacting cold-flow combustor with both dilution and film cooling holes that had measured turbulence levels of 20%.…”

Averaging Unsteady Non-Uniform Flow in Turbomashines for Efficiency Estimation

“…1 представлены данные математического моделирования не-стационарного вязкого течения, полученные методом прямого численного моделирования (DNS -Direct Numerical Simulation) [11].…”

“…В качестве примера регулярной пульсации скорости (давления) потока в ступени турбины на рис. 2 представлено изменение скорости и давления в фазовых координатах (скорость-давление), полученное в результате математического моделирования статор-ротор-взаимо-действия на конкретной турбине [11]. Здесь каждой точке графика соответствует свой момент времени, который не отражен на рисунке, чтобы не загромождать его.…”