Turbine blading designed for high heat load space propulsion applications

Abstract

The operating conditions and the propellant transport properties used in Earth-to-orbit (ETO) applications affect the aerothermodynamic design of ETO turbomachinery in a number of ways. This paper discusses some aerodynamic and heat-transfer implications of the low molecular weight fluids and high Reynolds number operating conditions on future ETO turbomachinery. The objective of this work was to examine turbine blading concepts for increasing life and reliability by reducing thermal heat load. Using the current Space Shuttle main engine high-pressure fuel turbine as a baseline, aerothermodynamic comparisons were made for two alternate fuel turbine geometries. The first was a revised first-stage rotor blade designed to reduce peak heat transfer. This alternate design resulted in a 23% reduction in peak heat transfer. The second design concept was a single-stage rotor designed to yield the same power output as the baseline two-stage rotor. Since the rotor tip speed was held constant, the turbine work factor doubled. In this alternate design, the peak heat transfer remained the same as the baseline. Although the efficiency of the single-stage design was 3.1 points less than the baseline two-stage turbine, the design was aerothermodynamically feasible and may be structurally desirable. NomenclatureC\ = slope of heat-transfer augmentation curve C p = specific heat c = chord D = leading-edge diameter e = kinetic energy loss coefficient h = heat-transfer coefficient / = enthalpy m = exponent in heat-transfer correlation N s = number of stages Nu -Nusselt number based on diameter Pr = Prandtl number p = pressure q -heat flux R = gas constant Re = Reynolds number based on blade leading-edge diameter T = temperature T u = turbulence intensity U = wheel speed V -absolute velocity v = specific volume W = relative velocity Z = compressibility factor a = absolute flow angle | 8 = relative flow angle 7 A/T = ratio of specific heats = output specific work = efficiencyPresented as Paper 88-3091 at the AIAA/ASME/SAE/ASEE 24th

Blade Heat Transfer Measurements and Predictions in a Transonic Turbine Cascade

“…Arts et al (1997), Dunn et al (1994), and Blair (1994) among others, showed midspan rotor blade leading edge heat transfer rates nearly twice the highest values seen elsewhere on the blade. Civinskas et al (1990) showed heat transfer in this region was reduced using a large leading edge diameter, and aerodynamic losses were not significantly increased. The rotor shape was chosen to achieve acceptable aerodynamics with a lower than typical ratio of peak-to-average heat transfer.…”

Prediction of Surface Roughness and Incidence Effects on Turbine Performance

“…Additional information regarding the tests was given by Hudson, Gaddis, Johnson, and Boynton(1991), Table I lists some of the flow and relevant geometric characteristics of this turbine at the design point. Further details of the geometry are given by Civinskas, Boyle, and McConnaughey(1990). The analysis was done using the mass flow at the design point pressure ratio for various wheel speeds.…”