A Phase I analytical program is proposed for an indirect means of reducing the temperature of gas turbine engine hot-section cooling air. The Indirect Cooling System (ICS) uses engine fuel as the heat sink in a manner similar to work already accomplished by the USAF IHPTET program. ICS provides additional advantages in terms of fire safety, reduction in exposure time to fuel deposit formation, the ability to remove and maintain the fuel heat exchanger and the ability to optimize the design of the fuel heat exchanger for reduced deposit rates independent of the design of the air heat exchanger. The program includes preliminary design of all hardware relating to the ICS, steady-state and transient code analysis of key components and the overall system, and code prediction of fuel deposit formation rates and their performance effects. Comparison will be made between ICS and the current IHPTET direct heat transfer approach. The program also includes definition of a fuel deposit test program including the detail design of the test hardware. This test program would further advance USAF high temperature fuel technology by focusing on the deposit influence of heat exchanger geometry, surface coatings, and high Reynolds number.
Benefits: The technology resulting from the proposed program is applicable to all gas turbine engines, including aircraft, ground vehicles, marine propulsion and industrial power generation. Reduction in engine cooling air temperature would enable higher engine specific power, longer life and reduced emissions.
