The proposal is for the design of a fan duct heat exchanger in order to improve aircraft fuel burn. The fan duct heat exchanger decreases the temperature of the 15% to 20% of compressor discharge air used to cool the High Pressure Turbine(HPT). Reducing the HPT cooling air temperature reduces the amount of cooling air needed for HPT cooling, and reducing vane and rotor blade cooling improves engine Specific Fuel Consumption(SFC). Fuel burn is adversely affected by any added engine weight due to the heat exchanger. Fan duct air is much colder than compressor discharge air, and can be used as a cold sink for cooling the HPT cooling air. Parametric analyses will be done to determine the SFC reduction as a function of cooling air temperature decrease. Pressure losses for both sides of the heat exchanger will be part of the analyses. The fan duct heat exchanger has large pressure differentials between the high pressure compressor discharge air and the relatively low pressure fan duct air. Structural analyses will be done for the heat exchanger to determine heat exchanger weight.
