Scaling Study of Wave Rotor Turbo-normalization of a Small Internal Combustion Engine.

摘要

One issue facing small Remotely Piloted Aircraft engines is their ability to maintain performance at altitude. Since many of these aircraft use commercial off the shelf engines originally designed for radio controlled aircraft and lawn care implements, the reduced pressure environment significantly degrades the operability of the engine as the altitude increases. An option to overcome this difficulty is to supercharge the system; however most superchargers are designed for larger, typically automotive, engines. As a supercharger's size is decreased, there are large efficiency losses. Therefore, there is a need to accomplish this function on a smaller scale without. One option is to utilize a device similar to the Comprex(registered trademark) wave rotor supercharger scaled for small engines. For this investigation, the author installed and evaluated the performance of a commercial Comprex(registered trademark) designed for a Mazda 626 2.0 liter diesel engine. The results were compared to simulation results from a one-dimensional computational fluid dynamics model. The loss models used by the code have been developed for and validated on wave machines designed for substantially higher corrected flow rates. Part of the current objective was to assess these scale related losses at a smaller scale. Results revealed a favorable comparison that demonstrates the loss models are applicable to the scale of the Comprex(registered trademark). The computational fluid dynamics code's ability to simulate a wide range of wave rotor sizes indicated the code could be used on a pressure wave supercharger scaled to fit today's Remotely Piloted Aircraft engines to predict performance. The wave rotor code predicts the performance of the scaled pressure wave supercharger to be similar to the full sized Comprex(registered trademark) providing approximately two times the ambient air pressure to the engine inlet.