Nozzle passage endwall effectiveness values with various combustor coolant flowrates-part 1: Flowfield velocity and coolant concentration measurements

The stators of the first stage of a gas turbine are exposed to severe temperatures. The coolant streams introduced to prevent the stators from thermal damage further complicate the highly three-dimensional vane passage flow. Recent results have shown that the coolant streams injected for cooling the combustor also influence the flow physics and the cooling effectiveness in the first-stage stator vanes passage. However, the effects of changing the mass flowrate of these combustor coolant streams on the passage flowfield have not been studied. As understanding the coolant transport is necessary for analyzing changes in cooling effectiveness in the vane passage, detailed aerodynamic and thermal measurements along the whole vane passage are required. This two-part paper presents such measurements taken for a variety of combustor coolant and endwall film coolant flowrates. The experiments were conducted in a low-Mach number facility with engine-representative Reynolds numbers and large-scale high-level turbulence. The objective of the first part is to describe the flow that influences endwall and vane surface cooling effectiveness distributions, which are presented in the second part. The measurements show changes in the passage flowfield due to changes in both combustor coolant and endwall film coolant flowrates. Overall, the flow physics remains largely unaffected by changes in coolant flowrates except in the endwall-vane surfaces region where the combustor coolant flowrate dominates changes in coolant transport. This is shown to have a high impact on endwall and vane surface cooling.