Download or read book A Simple Model of Pulsed Ejector Thrust Augmentation written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A simple model of thrust augmentation from a pulsed source is described. In the model it is assumed that the flow into the ejector is quasi-steady, and can be calculated using potential flow techniques. The velocity of the flow is related to the speed of the starting vortex ring formed by the jet. The vortex ring properties are obtained from the slug model, knowing the jet diameter, speed and slug length. The model, when combined with experimental results, predicts an optimum ejector radius for thrust augmentation. Data on pulsed ejector performance for comparison with the model was obtained using a shrouded Hartmann-Sprenger tube as the pulsed jet source. A statistical experiment, in which ejector length, diameter, and nose radius were independent parameters, was performed at four different frequencies. These frequencies corresponded to four different slug length to diameter ratios, two below cut-off, and two above. Comparison of the model with the experimental data showed reasonable agreement. Maximum pulsed thrust augmentation is shown to occur for a pulsed source with slug length to diameter ratio equal to the cut-off value.Wilson, Jack and Deloof, Richard L. (Technical Monitor)Glenn Research CenterTHRUST AUGMENTATION; MATHEMATICAL MODELS; FLOW VELOCITY; HARTMANN-SPRENGER TUBES; VORTEX RINGS; PULSED JET ENGINES; EJECTORS
Download or read book A Simple Model of Pulsed Ejector Thrust Augmentation written by and published by . This book was released on 2003 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Parametric Investigation of Thrust Augmentation by Ejectors on a Pulsed Detonation Tube written by Jack Wilson and published by BiblioGov. This book was released on 2013-08 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: A parametric investigation has been made of thrust augmentation of a 1 in. diameter pulsed detonation tube by ejectors. A set of ejectors was used which permitted variation of the ejector length, diameter, and nose radius, according to a statistical design of experiment scheme. The maximum augmentation ratios for each ejector were fitted using a polynomial response surface, from which the optimum ratios of ejector diameter to detonation tube diameter, and ejector length and nose radius to ejector diameter, were found. Thrust augmentation ratios above a factor of 2 were measured. In these tests, the pulsed detonation device was run on approximately stoichiometric air-hydrogen mixtures, at a frequency of 20 Hz. Later measurements at a frequency of 40 Hz gave lower values of thrust augmentation. Measurements of thrust augmentation as a function of ejector entrance to detonation tube exit distance showed two maxima, one with the ejector entrance upstream, and one downstream, of the detonation tube exit. A thrust augmentation of 2.5 was observed using a tapered ejector.
Download or read book Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector written by and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present NASA GRC-funded three-year research project is focused on studying PDE driven ejectors applicable to a hybrid Pulse Detonation/Turbofan Engine. The objective of the study is to characterize the PDE-ejector thrust augmentation. A PDE-ejector system has been designed to provide critical experimental data for assessing the performance enhancements possible with this technology. Completed tasks include demonstration of a thrust stand for measuring average thrust for detonation tube multi-cycle operation, and design of a 72-in.-long, 2.25-in.-diameter (ID) detonation tube and modular ejector assembly. This assembly will allow testing of both straight and contoured ejector geometries. Initial ejectors that have been fabricated are 72-in.-long-constant-diameter tubes (4-, 5-, and 6-in.-diameter) instrumented with high-frequency pressure transducers. The assembly has been designed such that the detonation tube exit can be positioned at various locations within the ejector tube. PDE-ejector system experiments with gaseous ethylene/ nitrogen/oxygen propellants will commence in the very near future. The program benefits from collaborations with Prof. Merkle of University of Tennessee whose PDE-ejector analysis helps guide the experiments. The present research effort will increase the TRL of PDE-ejectors from its current level of 2 to a level of 3. Santoro, Robert J. and Pal, Sibtosh Glenn Research Center NASA/CR-2003-212191, NAS 1.26:212191, E-13794
Download or read book THRUST AUGMENTED INTERMITTENT JET LIFT PROPULSION SYSTEM Pulse Reactor written by R. M. Lockwood and published by . This book was released on 1960 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Pulse Reactor consists of three properly shaped tubes: a valveless combustor, and two short jet thrust augmenters, plus a spark for starting ignition only, a starting air blast tube and a simple low-pressure fuel system. The engine has no moving parts, however, it is competitive in static or hovering performance with turbojet engines, having a thrust specific fuel consumption at this early stage of development of better than 1.0 pound of fuel per hour per pound of thrust. The effect of the intermittent jet thrust augmenters is to more than double the thrust of the intermittent jets that issue from both ends of the resonant combustor. This thrust augmentation, which is much greater than can be achieved with steady flow ejector type augmenters, is accomplished with devices that are relatively quite small. The effect of the thrust augmenter is to reduce the jet velocity at a distance of 7 jet outlet diameters downstream of the jet outlet to only about 190 feet per second and the temperature to about 200 deg F. The Pulse Reactor is quite insensitive to climatic and other environmental hazards. It has no problem from ingestion of foreign particles. The basic simplicity of the engine permits low cost development, production, and maintenance. Furthermore, it is practicable to build the engine in a wide variety of shapes to fit the requirements of aircraft design.
Download or read book Research Technology 2003 written by and published by DIANE Publishing. This book was released on with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Ejector Geometry on Thrust Augmentation for Pulse Detonation Engine Ejector Systems written by Ra'fat Shehadeh and published by . This book was released on 2007 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The major potential advantages of the PDE-ejector include reduced costs due to the reduced engine weight, along with improved specific fuel consumption and specific power inherent in the incorporation of a PDE component.
Download or read book An Experimental Investigation of Unsteady Thrust Augmentation Using a Speaker Driven Jet written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation is described in which a simple speaker-driven jet was used as a pulsed thrust source (driver) for an ejector configuration. The objectives of the investigation were twofold: first, to add to the experimental body of evidence showing that an unsteady thrust source, combined with a properly sized ejector generally yields higher thrust augmentation values than a similarly sized, steady driver of equivalent thrust. Second, to identify characteristics of the unsteady driver that may be useful for sizing ejectors, and predicting what thrust augmentation values may be achieved. The speaker-driven jet provided a convenient source for the investigation because it is entirely unsteady (having no mean component) and because relevant parameters such as frequency, time-averaged thrust, and diameter are easily variable. The experimental setup will be described, as will the various measurements made. These include both thrust and Digital Particle Imaging Velocimetry of the driver. It will be shown that thrust augmentation values as high as 1.8 were obtained, that the diameter of the best ejector scaled with the dimensions of the emitted vortex, and that the so-called Formation Number serves as a useful dimensionless number by which to characterize the jet and predict performance. Paxson, Daniel E. and Wernet, Mark P. and John, Wentworth T. Glenn Research Center NASA/TM-2004-212909, AIAA Paper 2004-0092, E-14332
Download or read book An Experimental Study of a Pulsed Jet Ejector written by Isaac M. Choutapalli and published by . This book was released on 2007 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first objective was addressed by carrying out direct thrust measurements on the free steady jet, free pulsed jet and the pulsed jet ejector configurations. Within the range of parameters investigated, it has been demonstrated conclusively that for an incompressible pulsed jet (Mj = 0.30) operating at a Strouhal number of around 0.1, thrust augmentation values as high as 1.9 can be obtained with a compact ejector (L/ D ≈ 3) at an area ratio (ejector inlet area/primary nozzle exit area) of about 11.0.
Download or read book Numerical Simulation of Steady and Pulsed Flows Through Thrust Augmenting Ejectors written by Emmanuel Chima Okpara and published by . This book was released on 2008 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector Nasa cr 2003 212191 National Aeronautics and Space Administr written by United States. National Aeronautics and Space Administration and published by . This book was released on 2003* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Thrust Augmentation Study of High Performance Ejectors written by John E. Minardi and published by . This book was released on 1983 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique is developed for determining a representative value of the maximum efficiency that can be achieved with high performance ejectors when operating on the supersonic solution branch of an ejector. These efficiencies are used to calculate thrust augmentation for an ejector over a wide range of parameters including operation with a hypothetical engine. Reasonable values of thrust augmentation can be achieved at low subsonic flight mach numbers. However, at flight Mach numbers near one, little or not thrust augmentation was found. At supersonic flight Mach numbers, thrust augmentation was achieved. Basic studies indicated that the effects of temperature was opposite at subsonic and supersonic flight Mach numbers. Thrust augmentation decreased with increasing temperature at subsonic Mach number sand increased with increasing temperature at supersonic Mach numbers.
Download or read book The Effect of Pulse Length and Ejector Radius on Unsteady Ejector Performance written by Jack Wilson and published by BiblioGov. This book was released on 2013-08 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thrust augmentation of a set of ejectors driven by a shrouded Hartmann-Sprenger tube has been measured at four different frequencies. Each frequency corresponded to a different length to diameter ratio of the pulse of air leaving the driver shroud. Two of the frequencies had length to diameter ratios below the formation number, and two above. The formation number is the value of length to diameter ratio below which the pulse converts to a vortex ring only, and above which the pulse becomes a vortex ring plus a trailing jet. A three level, three parameter Box-Behnken statistical design of experiment scheme was performed at each frequency, measuring the thrust augmentation generated by the appropriate ejectors from the set. The three parameters were ejector length, radius, and inlet radius. The results showed that there is an optimum ejector radius and length at each frequency. Using a polynomial fit to the data, the results were interpolated to different ejector radii and pulse length to diameter ratios. This showed that a peak in thrust augmentation occurs when the pulse length to diameter ratio equals the formation number, and that the optimum ejector radius is 0.87 times the sum of the vortex ring radius and the core radius.
Download or read book Workshop on Thrust Augmenting Ejectors written by and published by . This book was released on 1979 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Aerospace Sciences Meeting and Exhibit 42nd written by and published by . This book was released on 2004 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Pulse Detonation Rocket Induced MHD Ejector PDRIME Concept Preprint written by and published by . This book was released on 2008 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulse detonation engines (PDEs) have received significant attention due to their potentially superior performance over constant pressure engines. However due to the unsteady chamber pressure, the PDE system will either be over- or under-expanded for the majority of the cycle, with substantial performance loss in atmospheric flight applications. Thrust augmentation, such as PDE-ejector configurations, can potentially alleviate this problem. Here, we study the potential benefits of using Magneto-hydrodynamic (MHD) augmentation by extracting energy from a Pulse Detonation Rocket Engine (PDRE) and applying it to a separate stream. In this PDRE-MHD Ejector (PDRIME) concept, the energy extracted from a generator in the nozzle is applied directly to a by-pass air stream through an MHD accelerator. The air stream is first shocked and raised to high-temperature, allowing thermal ionization to occur after appropriate seeding. The shock-processing of the high-speed air stream is accomplished by using the high initial PDRE nozzle pressures of the under-expanded phase. Thus, energy could be efficiently transferred from one stream to another. The present simulations involve use of a simple blowdown model for PDE behavior, coupled to quasi-1D and 2D numerical simulations of flow and MHD processes in the rest of the PDRIME configuration. Results show potential performance gains but some challenges associated with achieving these gains.
