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 Performance of Thrust Augmenting Ejectors written by Paul Allen Van and published by . This book was released on 1971 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Entrainment and Mixing in Thrust Augmenting Ejectors written by L. Bernal and published by . This book was released on 1982 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments have been performed with subsonic and underexpanded choked two-dimensional primary nozzle ejector flow system without diffusion to evaluate the role of entrainment and mixing in thrust augmentation. Two-component Laser Doppler velocity measurements (mean and fluctuating values), thrust measurements, ejector shroud surface pressure measurements and flow visualization were used to determine the evolution of the velocity profiles and their relationship to the ejector performance.

Download or read book Experimental Investigation of a Thrust Augmenting Ejector written by Hidayat Wiradimadja and published by . This book was released on 1985 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An ejector is basically a jet pump in which the kinetic energy of the jet is made to impart motion to the fluid surrounding it. During this process, in a well design system, the ejector as a whole experiences a thrust much higher than that of the jet alone. In principle, an ejector is nothing but a jet surrounded by a shroud. This investigation concerns the performance of a two- dimensional ejector with its primary jet excited by a novel method. A constant area duct was used in this experiment. The velocity of the jet at the exit was subsonic. Maximum thrust was obtained when the ejector to jet exit area ratio was about 35. Under this condition a thrust augmentation ratio of 1.65 was achieved, with the jet excited at 20 Hz, whereas without excitation it was only 1.40. The mixing characteristics of the jet under excitation was examined using flow visualization techniques. Smoke filaments illuminated by a sheet of powerful light and schlieren optics with the jet heated were used. Excitation of the jet was found to generate large vortex-like flow structures which might be responsible for enhanced mixing. These vortices extended to considerable distances on both sides of the jet.

Download or read book Experimental Investigation of High Performance Short Thrust Augmenting Ejectors written by and published by . This book was released on 1983 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results of an experimental investigation concerning the design and testing of air-to-air thrust augmenting ejectors utilizing short curved-wall diffusers are presented. These ejectors were designed primarily according to the procedure established in an analytical research effort sponsored by DTNSRDC from 1980-1981. Two of the three ejectors tested have identical mixing chambers. The mixing chamber inlet area to the primary nozzle area ratio lambda was 40. The overall ejector length-to-mixing chamber diameter ratios L/D(overall) were 6.09 and 6.16; diffuser area ratios AR(diff) were 1.33 and 1.46, respectively. The third ejector had an L/D(overall) of 6.02, a lambda of 20 and an AR(diff) of 1. 26. The best observed thrust augmentation ratio phi and the modified thrust augmentation ratio phi sub 2 were 2.11 and 1.91 respectively for a sonic primary jet. The modified thrust augmentation ratio phi sub 2 accounts for the penalty of suction in preventing flow separation in the diffuser. These levels of thrust ratio were derived from velocity measurements at the ejector exit. Independent thrust measurements obtained with strain gages on the mixing chamber agree with the force calculated from the momentum data. The experimentally observed ejector performance data correlated well with the predicted values. (Author).

Download or read book A Theoretical Study of Two Stage Thrust Augmenting Ejectors written by A. M. Abdel-Fattah and published by . This book was released on 1984 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of theoretical assessment of two stage thrust augmenting ejectors are presented and compared with those of single stage ejectors. The mixing ducts were of constant cross sectional area, the flows at the inlet and exit planes of each stage were assumed to be uniform, and friction effects were ignored. It was found that staging the ejector increases thrust augmentation at all primary jet stagnation pressures, but is more effective in the low pressure range and with high ejector area ratios for any gas combination. With a Hot Rocket-Air combination, the benefit of staging is much less than with an unheated Air-Air combination, and does not appear to be of practical use.

Download or read book Applicability of Thrust Augmenting Ejectors in a Supersonic Cruise Configuration written by Wendell S. Hertzelle and published by . This book was released on 1997-04-01 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thrust augmenting ejectors were analyzed by the author in an attempt to see if they could be used to provide a significant thrust increase over the baseline thrust of a primary core. This was done for the purpose of determining if leaving the ejectors open in the cruise configuration of the High Speed Civil Transport would lead to a thrust increase that would at least offset the weight of the ejectors themselves. If this was found to be true then the fuel economy of the HSCT might be improved by leaving them open and not closing them during cruise. In analyzing the ejectors, no assumptions were made regarding inlet nor outlet configurations, so an attempt was made to find the point of optimal thrust augmentation by varying secondary stream bypass Mach number and the amount of flow entrainment. Two solutions were found to each mixing scenario, one subsonic and the other supersonic. These two solutions were each analyzed and ones not satisfying the Second Law of Thermodynamics were eliminated. Analytic diffuser and bleed losses were also explored in the analysis of the ejector flow. Within the limitations of the assumptions discussed in this paper, appreciable thrust augmentations have been discovered over a large range of bypass Mach numbers and entrained mass flows. This lead the author to the conclusion that ejectors warrant further research beyond a first order analysis, and serious thought should be put into leaving them open in cruise.

Download or read book Thrust Augmenting Ejectors written by Morton Alperin and published by . This book was released on 1981 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion of the development of the compact jet-diffuser ejectors utilized for hovering and low speed flight propulsion has been presented. This is followed by a description of ideal ejector performance as derived from a compressible flow theory, over the range of flight speeds from zero to supersonic speed. These analyses introduced the concepts of ejector configuration optimization and the validity of the so-called 'second solution' to the mixing problem, wherein the flow after complete mixing is supersonic. The ideal performance of thrust augmenting ejectors designed under this 'second solution' has been shown to be far superior to those designed by conventional methods. The ability of properly designed ejectors to utilize the thermal energy of injected gas for the production of useful energy has also been described. Finally, the influence of major losses has been discussed, including means for avoiding excessive performance degradation by proper optimization of the geometry of the ejector in view of these losses.

Download or read book Inlet and Diffuser Effects on Thrust Augmenting Ejectors written by S. G. Reznick and published by . This book was released on 1982 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effects of primary jet inlet nozzle configuration and diffuser geometry on the thrust augmentation of circular and rectangular ejectors are investigated in an experimental study. The rectangular ejector inlet nozzle configurations consist of either one, two, or three slot nozzles. The circular ejector inlet nozzles consist of slot nozzles placed either across the inlet or around the inlet periphery. Diffuser geometry is varied primarily by changing the diffuser area ratio. Effect on thrust performance of the primary flow injection angle relative to the inlet walls is investigated. Effects of side-wall, end-wall, and diffuser blowing on thrust performance and diffuser stall also are considered.

Download or read book An Experimental Investigation of Two Dimensional Thrust Augmenting Ejectors written by L. Bernal and published by . This book was released on 1984 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments were performed with subsonic and underexpanded choked two-dimensional primary nozzle ejector flow systems without diffusion to evaluate the role of entrainment and mixing in thrust augmentation. Two-component Laser Doppler velocity measurements (mean and fluctuating values), thrust measurements, ejector shroud surface pressure measurements and flow visualization were used to determine the evolution of the velocity profiles and their relationship to the ejector performance. Key findings include: (1) Primary jet growth is significantly altered by the ejector shroud. (2) Primary jet turbulent characteristics when normalized with the local mean centerline velocity are in agreement with those for the free-jet. (3) In the neighborhood of the ejector shroud the flow field can be classified into two regions--the potential flow region and the region close to the ejector exit which is dominated by the turbulent transport. (4) Pressure recovery is very sharp in the first region and is more gradual in the region close to the ejector exit. The investigation is continuing toward the near-term objectives of obtaining measurements within diffused flow and with heated primary air. This volume emphasizes the laser doppler velocimetry developed especially for this program. Part II (AD-A154 083) presents detailed cold flow measurements along with preliminary primary hot flow data.

Download or read book Experimental Investigation of Thrust Augmenting Ejectors Using Vane Excited Primary Jets written by and published by . This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation has been conducted to evaluate the entrainment characteristics of a thrust augmenting ejector, with a small, oscillating airfoil inserted in the potential core of the primary jet. Velocity distributions were measured across the width of the jet, at downstream distances of 20 and 40 nozzle widths, with the jet exhausting into still air and with the jet exhausting into an instrumented ejector shroud for the following range of parameters: Pressure ratio 1.137 and 1.268, amplitude of oscillation 2.6 deg and 6.9 deg zero-to-peak frequency of oscillation 0, 20, 40 and 60 Hz. Static pressure distributions were measured within the shroud when the jector was installed. The results amplify previously conducted studies. Jet spreading and entrainment appear to increase with increasing amplitude and frequency of oscillation and to decrease with increasing nozzle pressure ratio. (Author).

Download or read book Study of Three Dimensional Thrust Augmenting Ejectors written by Ramesh K. Agarwal and published by . This book was released on 1982 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: A theory is presented for the prediction of thrust augmentation characteristics of a three-dimensional ejector configuration in which a series of rectangular-hypermixing nozzles pumps the secondary air in a constant-area or slowly diverging channel. Based on the theory, a computer program is developed which requires the ejector design parameters, the empirical constants in the eddy viscosity model, and the nozzle pressure ratio as input and calculates the entrained secondary mass flow, the secondary and exit velocities, the net thrust and the thrust augmentation ratio. Good agreement is found between the theoretical prediction and the experimental data.

Download or read book Lifting Surface Theory for Thrust Augmenting Ejectors written by P. M. Bevilaqua and published by . This book was released on 1982 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: The circulation theory of airfoil lift has been applied to predict the static performance of thrust augmenting ejectors. The ejector shroud is considered to be 'flying' in the velocity field induced by the entrainment of the primary jets, so that the thrust augmenting force is viewed as analogous to the lift on a wing. Vortex lattice methods are used to compute the augmentation from the surface pressures on the shroud. The thrust augmentation is shown to depend on the length and shape of the shroud, as well as its position and orientation. Predictions of this new theory are compared with the results of classical momentum theories for calculating the augmentation from the stream thrust. (Author).

Download or read book Thrust Augmenting Ejectors written by K. S. Nagaraja and published by . This book was released on 1993 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Thrust Augmenting Ejectors written by and published by . This book was released on 1983 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: An automated thrust augmentation data acquisition facility was designed and constructed. The facility provides the capability of measuring thrust augmentation ratio and mass flow augmentation ratio. A three dimensional graphics plot of exit flow is provided for flow analysis. Tests were conducted on a 4.4 in. diameter circular ejector, with eight primary nozzles mounted symmetrically along the perimeter of the inlet. A fixed ejector geometry was used. The ratio of mixing chamber area to diffuser exit area was 1.88. The fluid injection angle, measured from a line perpendicular to the ejector centerline, was varied and the thrust augmentation and mass flow augmentation ratios calculated. Both thrust augmentation and mass flow augmentation increased with fluid injection angle to the stall point where both decreased. Axial flow symmetry of primary air was found to affect stall along diffuser walls.

Download or read book Thrust Augmenting Ejectors written by Viets, Hermann and published by . This book was released on 1975 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Experimental Study of Rectangular and Circular Thrust Augmenting Ejectors written by and published by . This book was released on 1981 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: A short rectangular ejector and two circular ejectors were tested to determine the effects of primary nozzle configuration and geometry on thrust augmentation. The primary nozzle configurations consisted primarily of slot nozzles which injected fluid parallel to the diffuser walls and achieved Coanda type flow at the throat. Results of the rectangular ejector tests indicate that thin plates installed in the mixing chamber or the diffuser, increase mixing but decrease thrust augmentation. A continuous slot nozzle, modified to create four discrete jets at the inlet, improved mixing and thrust augmentation compared to the original design. Thrust augmentation ratio increased from 1.4 to 1.58. The circular ejector primary nozzles consisted of a continuous slot 'torus' nozzle and individual slot nozzles which could be symmetrically placed around the inlet periphery. A nozzle configuration using 16 slot nozzles on the periphery of the inlet face gave the best performance. A thrust augmentation ratio of 2.0 was achieved.