Evaluation of Hypermixing for Thrust Augmenting Ejectors

Abstract

Steady-state distortion levels produced during full scale P 3 G operation as evaluated in terms of IDC (circumferential) and IDR (radial) distortion parameters were generally less 0.02 and nominally 0.01 or less as previously realized in the model test. Figure 10 summarizes the circumferential planarity in terms of phase and amplitude. The probe readings from two of the rakes, 180° apart, at the engine IGV plane were averaged to obtain these summary results. Such a comparison indicates excellent circumferential planarity over the complete range of the test data.A similar summary of radial planarity characteristics is presented in Fig. 11. In this case, all the probe readings from 2 selected radial immersions were averaged. Radial immersion B is the tip and D is the hub ring. The hub ring probes had the most deviation from those in any of the other rings, thus the results of Fig. 11 represent the "worst case." VII. ConclusionsIt has been shown that the P 3 G (Planar Pressure Pulse Generator) a new dynamic distortion generator, has produced discrete frequency pressure waveforms of high quality which are controllable in both amplitude and frequency. This has been accomplished over a wider range of amplitude, frequency and airflow than reported in the literature for other discrete frequency distortion devices. Application of P 3 G type devices in component and engine stability testing should permit: 1) More comprehensive experimental isolation and study of unsteady aerodynamic instability phenomena than previously possible.2) Establishment of a data base for validation of high speed turbine machinery dynamic math models at the higher frequencies of recent concern.VIII. References iMeyer, C. L., McAulay, J. E., and Biesiadany, T. J., 'Technique for Inducing Controlled Steady-State and Dynamic InletThe additional thrust required to give an aircraft VSTOL capability may be obtained by diverting the exhaust of the cruise engine through a thrust augmenting ejector. The hypermixing nozzle has been developed to increase the rate of jet mixing and thereby improve the performance of the ejector. Since this is achieved at some cost in primary thrust efficiency, comparison tests were performed with a single shroud and three interchangeable nozzles. A one-dimensional analysis is used to compute ideal levels of augmentation and assess the relative importance of the injection losses. It is seen that hypermixing significantly improves ejector performance by making efficient diffusion of the mixed flow possible. Nomenclature A = area c p -specific heat at constant pressure c v = specific heat at constant volume rfi = rate of mass flow n = transfer efficiency of the mixing process P -fluid pressure T = fluid temperature V = flow velocity j3 = measure of profile curvature 77 = nozzle thrust efficiency p -fluid density 0 = thrust augmentation ratio Subscripts 0 = ejector inlet condition, primary flow 1 = ejector inlet condition, entrained flow 2 = diffuser inlet condition, mixed flow 3 = diffuser exhaust condition, mixed flow * = isent...

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