N&R Engineering worked with NASA Glenn Research Center on a SBIR Phase I project titled: “Fan Duct Heat Exchanger for Turbine Cooling Air.”
The objectives of this project were: 1) The improvement in engine thermal efficiency due to cooling the compressor discharge air, and 2) The increased engine weight due to a fan duct heat exchanger.
Fan duct air is much cooler than compressor discharge air, and can be used to lower the fraction of compressor discharge air that is used to cool the High Pressure Turbine (HPT). Because HPT cooling air requirements vary dramatically with cooling air temperature, lowering this temperature improves engine efficiency. However, compressor discharge air is at a much higher pressure than fan duct air, and the heat exchanger weight could be significant.
The tasks required to address the objectives of this work were:
- Determine Specific Fuel Consumption (SFC) improvement as a function of the fan duct heat exchanger effectiveness for a range of parameters.
- Include required vane and blade coolant for temperatures consistent with future coated metallic and CMC materials.
- Include the effect on SFC of using an auxiliary compressor to ensure a positive backflow pressure margin for the first stage HPT vane.
- Determine heat exchanger size for variations in heat exchanger effectiveness.
- Analyze fan duct side heat transfer and pressure loss characteristics.
- Perform structural analysis to determine required material thicknesses and heat exchanger weight.
- Determine the effect on fuel burn due to decreased coolant temperature, heat exchanger weight, increased fan duct pressure drop, and auxiliary compressor.
For more in-depth detail, please reference the following figure below.
This project is expected to continue through the remainder of 2016. If you have questions regarding this project or our capabilities, please contact us.