Fully Cooled Single Stage HP Transonic Turbine—Part II: Influence of Cooling Mass Flow Changes and Inlet Temperature Profiles on Blade and Shroud Heat-Transfer

Abstract

A fully cooled transonic high-pressure turbine stage is utilized to investigate the combined effects of turbine stage cooling variation and vane inlet temperature profile on heat transfer to the blades with the stage operating at the proper design corrected conditions. For this series of experiments, both the vane row and the blade row were fully cooled. The matrix of experimental conditions included varying the cooling flow rates and the vane inlet temperature profiles to observe the overall effect on airfoil heat-transfer. The data presented in Part I focused on the aerodynamics of the fully cooled turbine for a subset of the cases investigating two vane inlet temperature profiles (uniform and radial) and three different cooling levels (none, nominal, and high) for the high Reynolds number condition. This part of the paper focuses on the time-average heat-flux measurements on the blade and shroud region for the same cooling mass flow rates and vane inlet temperature profiles. The cooling effects are shown to be small and are centered primarily on the suction side of the airfoil. This relatively small influence is due to the ratio of the cooling gas to metal temperature being closer to 1 than the design value would dictate. The vane inlet temperature profile effects are more dominant, and using a net Stanton number reduction factor to compare the cases, an effect on the order of about 0.25 is demonstrated. This effect is due primarily to the change in the reference temperature used for the Stanton number calculation. The differences due to profile effects are small but observable toward the trailing edge of both the blade and rotor shroud. This data set forms an excellent baseline for heat-flux calculations, as the variation in the main input conditions are well documented and do not produce large changes in the heat-flux. It provides insight into the flow physics of an actual engine and guidelines about proper normalization of variables for a cooled turbine stage, supporting further development of computational heat-flux modeling techniques.

Unsteady Heat Transfer and Pressure Measurements on the Airfoils of a Rotating Transonic Turbine With Multiple Cooling Configurations

“…It can also produce radial and hot-streak temperature profiles (see Refs. [12][13][14][15][16][17][18][19]), but the inlet temperature profile was kept constant for this experiment. Downstream of the emulator, the flow enters a nozzle guide vane, and rotor, which is spun up to about 98% design-speed prior to the experiment, and freely accelerates up to about 102% before the FAV is closed.…”

Experimental and Numerical Investigation of Optimized Blade Tip Shapes: Part I — Turbine Rainbow Rotor Testing and CFD Methods

“…Despite the potential of shape design to control the tip flows, very scarce information is available in the open literature on the gap flow physics of alternative tip configurations. Furthermore, the optimization methods and the numerical models employed for their design necessitate validation through experimental data collected at engine representative conditions [15,16]. While a large part of the research works exploits low-speed linear cascade testing to investigate novel tip seals [17], high-speed testing is required to simulate the flow structures inside the tip gap at engine representative Mach numbers [18,19].…”

An Investigation of Coolant Within Serpentine Passages of a High-Pressure Axial Gas Turbine Blade

“…Abhari and Epstein [3] performed an experiment with five rows of cooling holes and quantified average blowing and momentum ratios for two of the rows but did not quantify blowing for the other rows or investigate spanwise discrepancies in cooling flows within a row. A more recent experiment reported by Haldeman et al [4] quantifies total rotor cooling as a percentage of total core flow but does not quantify cooling flows on a row-by-row basis or provide any blowing ratio values.…”