Fractal Heat Exchanger for Gas Turbine Pre-Cooling

ABSTRACT: Physical Sciences, Inc. (PSI) has developed a novel heat exchanger based on the mathematical concept of fractal branching. The branching structure allows the heat exchanger to discard much of the weight that other designs require for flow manifolds and structural support. The new heat exchanger is more efficient and light enough to use on an airplane engine.When used on a high speed (Mach 4) airplane, the heat exchanger allows use of current engine technology via pre-cooling. Pre-cooling is cooling of the engines intake charge to allow operation at higher speeds than would normally be possible.Initial analysis indicates that the PSI heat exchanger can reduce temperatures sufficiently to enable existing engines such as the F-119 to greatly expand their operating envelope to Mach 4. System performance is increased; development cost of a high speed engine will also be reduced by reliance on proven designs.A test article will be produced with heat transfer rate of 30 kW/lbm, and future research could produce power-to-weight ratios of 100 kW/lbm or more. These weight reductions are a major improvement over the 8 kW/lbm state of the art. This advance is made possible through new numerical optimization techniques and additive manufacturing of metals.; BENEFIT: A major potential benefit of this research is for existing engine designs to be operable at speeds of Mach 4 or greater. Existing gas turbine engines are normally only operable up to Mach 2, with some advanced designs going to Mach 3.2 or so. Re-use of existing designs and design methodology would save development time and cost for high speed propulsion, and increase efficiency of high speed airplanes.The light weight geometry pursued by PSI is also applicable to recuperation of gas turbines and intercooling of internal combustion engines, two major areas of potential efficiency increase for airplanes, helicopters, and ground vehicles. The approach pursued in this research can also be applied to super-compact heat exchangers for electronics and micro engines.