Design and Fabrication of an Experimental Test Facility to Compare the Performance of Pulsed and Steady Flow through a Turbine

Abstract

Modern aircraft are almost entirely powered by gas turbine engines (GTEs). Improving the e ciency is a constant topic in the GTE eld and pulse detonation engines (PDEs) are being investigated as a possible way to increase the e ciency of the modern GTE. The rst advantage lies in decreased fuel consumption since the PDE cycle consumes fuel in short bursts instead of a constant stream. The second advantage comes from the pressure rise associated with the near constant volume combustion of PDEs. A pressure rise in the combustion chamber of a GTE would decrease the number of necessary compressor stages to achieve a desired turbine inlet pressure. This in turn decreases the amount of work required to drive the compressor. The engine could be downsized or the extra work could be used to produce more thrust. The use of PDEs as a viable component of GTEs has been established experimentally both in a ight test and in the lab. In 2008, the Air Force Research Laboratory at Wright-Patterson Air Force Base used a PDE to propel an aircraft. Although not conclusive, laboratory results obtained by Rasheed et al. show that the integration of PDEs into GTEs have potential e ciency increases. Despite the potential advantages, the e ects of the pressure pulses created by pulse detonations on the turbine are not well understood. The successful integration of PDEs into GTEs requires a better understanding of turbine performance under pulsed conditions. The objective of the current work is to design a test facility to compare turbine performance under steady conditions with turbine performance under pulsed conditions. This work builds on research by previous authors who have also performed experiments to compare the performance of a PDE driven turbine with the performance of a steady ow driven turbine. Rouser et al. experimentally examined radial turbine performance under pulsed ow. The e ects of pulsed ow on axial turbines, however, is the topic addressed by this paper. Previous work on pulsed ow through an axial turbine used a mixing region to combine PDE exhaust with bypass air to mitigate the negative e ects of high temperature on the turbine. This bypass region also dampened the pressure pulse seen by the turbine. The current work uses compressed air in place of combustion gases to drive an axial turbine. The use of compressed air to create the pressure pulses allows for direct coupling of the turbine and pressure pulse, thus providing a better picture of the e ect of pulsed ow on axial turbine performance than has been accomplished in previous work.