1992 · 108 citations · 0 references
EngineeringMechanical EngineeringPhysicsAerodynamicsFluid DynamicsHeat TransferCooling SystemsEngine CoolingEngine Heat TransferHeat Transfer AnalysisHeat Transfer In FluidsTransonic AerodynamicsBlade CoolingCoolingFilm CoolingRotor CoolingTurbine Blade AerodynamicsTurbine Blade CoolingTurbine CoolingTurbines
Time‑resolved heat‑transfer measurements were performed on a fully cooled transonic turbine stage in a short‑duration test facility that simulates full engine nondimensional conditions, and the time‑averaged data were compared to uncooled rotor data and cooled linear cascade measurements on the same profile. Film cooling reduced time‑averaged heat transfer on the blade suction surface by up to 60 % (with little effect on the pressure surface), was less effective at high blowing ratios, and, when effective, lowered the dc heat‑transfer level and altered the unsteady waveform, with unsteady blowing driving fluctuations and a linear model accurately predicting the resulting 12 % suction‑surface decrease and 5 % pressure‑surface increase.
Time-resolved measurements of heat transfer on a fully cooled transonic turbine stage have been taken in a short duration turbine test facility, which simulates full engine nondimensional conditions. The time average of this data is compared to uncooled rotor data and cooled linear cascade measurements made on the same profile. The film cooling reduces the time-averaged heat transfer compared to the uncooled rotor on the blade suction surface by as much as 60 percent, but has relatively little effect on the pressure surface. The suction surface rotor heat transfer is lower than that measured in the cascade. The results are similar over the central 3/4 of the span, implying that the flow here is mainly two dimensional. The film cooling is shown to be much less effective at high blowing ratios than at low ones. Time-resolved measurements reveal that the cooling, when effective, both reduced the dc level of heat transfer and changed the shape of the unsteady waveform. Unsteady blowing is shown to be a principal driver of film cooling fluctuations, and a linear model is shown to do a good job in predicting the unsteady heat transfer. The unsteadiness results in a 12 percent decrease in heat transfer on the suction surface and a 5 percent increase on the pressure surface.