Double-walled Combustor Liner Studies
To understand the complex heat transfer characteristics that arise along a cooled combustor liner, conjugate heat transfer studies have been conducted on a public geometry containing a double wall with effusion and dilution holes. The facility features both effusion cooling and dilution jet interactions representative of advanced RQL combustion systems. The data highlights critical cooling effects near the dilution hole. Additionally, the double-walled configuration features complex impinging flows that are representative of cooling technologies widely used in modern gas turbine engines. Measurements were acquired of surface temperature (infrared thermography) and the near-wall flowfield (PIV) are available at multiple dilution jet momentum flux ratios and freestream turbulence intensities.
Zoomed in view of the double wall liner including inward facing effusion cooling near the dilution jet; impingement surface is on the bottom while the hot side is on the top. (Right) Overall effectiveness contours shown on the hot side of the liner (blue denotes higher effectiveness).
The double-walled combustor liners that were experimentally studied in large scale models included three different versions of the effusion hole geometry. The three versions varied the effusion hole pattern in the immediate vicinity of the large primary dilution holes. Specifically, the row of effusion holes forming a circle around and located closest to the large dilution holes were oriented in three different patterns that included (1) an inward pattern facing toward the dilution holes, (2) an outward pattern facing away from the dilution holes, and (3) a case with the effusion holes closed off with no flow. A small difference in the effusion hole diameter and the wall thickness between the experiment and model were found to result in noticeable differences in effusion flow behavior and wall temperatures. Therefore recent measurements of the diameter of the effusion holes were provided as well as measurements of the liner wall thicknesses to ensure the precise geometric dimensions from the experiment were incorporated into the conjugate simulations.
Experimental setup at Penn State showing the test rig, PIV laser system, and the three double-wall combustor liner panels that were studied and provided.
Additional experimental data sets and analysis results were also provided by Penn State for the three different effusion hole pattern cases. The data included measurements of liner wall surface temperature using infrared thermography (IR) and measurements of mainstream flow velocity using particle image velocimetry (PIV). The flow field data included velocity magnitudes and turbulence intensity levels in the streamwise centerline-plane of the dilution jets for an elevated dilution flow momentum flux ratio of approximately I = 30, which is representative of combustor flow conditions in actual gas turbine engines. An example of the measured flow field in the center-line plane of the dilution jets for the inward facing effusion hole pattern is shown. The contour plot of turbulence includes superimposed velocity streamlines that show a complicated and intense flow field in the vicinity of the dilution hole with large velocity gradients. The resulting flow field circulation patterns that develop entrain the near wall effusion cooling flow adjacent to the dilution hole upwards away from the liner thus removing the protective cooling air from the combustor walls.
Experimental flow field data taken with PIV measurements within the dilution jet centerline-plane for the inward facing effusion cooling hole pattern showing contours of turbulence.