Advances in Ejector Technology - A Tribute to Hans von Ohain's Vision
AIR FORCE WRIGHT AERONAUTICAL LABS WRIGHT-PATTERSON AFB OH FLIGHT DYNAMICS LAB
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A great deal of fundamental investigations and applied research has been performed in the area of ejectors as jet pumps over a period of several decades. However, it is only recently that ejectors are recognized as thrust augmentors since the early work of Von Karman. Subsequently, U. S. Air Force undertook a project of developing the ejector technology for thrust augmentation purposes. A great deal of fundamental and applied work was performed in the course of the last fifteen to twenty years, and a considerable amount of the results has been published. Following are some of the significant and fundamental developments in thrust augmenting ejectors that resulted from ARLs studies 1 Development of hypermixing nozzles for mixing enhancement was achieved 2 Demonstration that mixing and diffusion of flows could be done simultaneously with performance advantage was accomplished 3 An incompressible ejector analysis which will parametrically evaluate an ejector performance was performed 4 Thrust augmentation of the order of two in an ejector of inlet area ratio 23 was successfully achieved experimentally 5 Good thrust augmentation for VSTOL purposes was also realized by using full- scale multichannel ejectors. 6 It was demonstrated that diffusion normal to the plane of the velocity profile always leads to improved mixing in contrast to diffusion in the plane of the velocity profile 7 An ejector-wing model was designed, fabricated and tested and 8 Further compactness of the ejector was realized by the utilization of a device that combines efficient boundary-layer energization with a configured diffusion device, that is, trapped vortex cavity.
- Jet and Gas Turbine Engines