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 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 Thrust Augmenting Ejector Flows written by L. Bernal and published by . This book was released on 1982 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of two investigations, one recently completed on pulsatile ejector flows and the second currently in progress on a two-dimensional ejector configuration are presented. The objective of these investigations is to determine the role of entrained fluid and its mixing with the primary jet on ejector performance. Results will also be presented on the effects of entrance geometry on ejector entrainment and thrust augmentation.
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 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 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow-field within a two-dimensional thrust augmenting ejector has been documented experimentally. Results are presented on the mean velocity field and the turbulent correlations by laser doppler velocimeter, surface pressure distribution, surface temperature distribution, and thrust performance for two shroud geometries. The maximum primary nozzle pressure ratio tested was 3.0. The tests were conducted at primary nozzle temperature ratios of 1.0, 1.8, and 2.7. Two ejector characteristics lengths were identified based on the dynamics of the ejector flow field--a minimum length below which no significant mixing occurs, and a critical length associated with the development of U'V' correlation in the ejector. These characteristic lengths divide the ejector flow field into three distinctive regions: the entrance region where there is no direct interaction between the primary flow and the ejector shroud; the interaction region where there is an increased momentum of induced flow near the shroud surface; and a 'pipe' flow region characterized by an increased skin friction. The effect of the coflowing induced flow shown to produce inside the ejector a centerline velocity that increased over the free-jet data. The normalized turbulent correlations are found to be 25% lower than those in free jets. Effects of pressure ratio on the ejector flow field are small. Present measurements also show that the ejector performance was not influenced by the primary nozzle temperature ratio up to 2.7.
Download or read book Experimental Investigation of Thrust Augmenting Ejectors Using Vane Excited Primary Jets written by Thomas Robert McClellan and published by . This book was released on 1982 with total page 143 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 Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 An Experimental Investigation of a Circular Thrust Augmenting Ejector written by Generoso C. Uhuad (CAPT, USAF.) and published by . This book was released on 1986 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Ejector Thrust Augmentation written by Alton Alfred Eichelkraut and published by . This book was released on 1960 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Ejector Thrust Augmentation written by Alton Alfred Eichelkraut (CAPT, USAF.) and published by . This book was released on 1960 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical Investigation of High Performance Short Thrust Augmenting Ejectors written by Tah-Teh Yang and published by . This book was released on 1982 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: A procedure for analyzing thrust augmenting ejectors having a short, curved-wall diffuser is presented. In this type of diffuser a shear flow is admitted at the inlet and a set of auxiliary ejectors is used to provide the necessary boundary layer control. Several computer programs are used in the analytical procedure. These computer programs are either outlined or referenced in the open literature. A user's manual is provided in the Appendices of this report. A discussion of the geometries and performances, including thrust augmentation ratios, of two sample ejectors determined by use of this analytical procedure with mixing chamber contraction as an optimization parameter is presented. Use of the mixing chamber length as an optimization parameter is also discussed. (Author).
Download or read book An Experimental Investigation of New Concepts in Ejector Thrust Augmentation for V stol written by Morton Alperin and published by . This book was released on 1969 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic concept involved in the investigation is the utilization of the Coanda effect in combination with an external cascade of airfoils. That combination served to achieve a more efficient rotation and amplification of the jet thrust vector as a result of both the large induced mass flow from the environment and the simultaneous high lift of the cascaded airfoils. The program objective was to establish optimal performance by systematic variation of the pertinent parameters. Experimental results showed a gain of 20% in augmented thrust compared to that of a simple Coanda cylinder. Since the observed mass flow through the airfoil cascade was small, in-house tests were performed with diffusion. The resultant increase in secondary mass flow produced a gain of 65% in thrust augmentation over the tests without diffusion despite large regions of flow separation in the diffuser. It appears highly probable that further large gains can result from precise diffuser design and boundary layer control in the diffuser. (Author).
Download or read book An Experimental Investigation of a Circular Thrust Augmenting Ejector written by Generoso C. Uhuad and published by . This book was released on 1985 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: A 4.4 in diameter circular ejector was tested to determine the effect on thrust augmentation ratio of the primary nozzle height and injection angle. Also tested were the effects of alternating primary nozzle injection angles, diffuser blowing and suction, inlet cross flow and low primary nozzle exit velocities on thrust augmentation. The results showed that both the primary nozzle injection angle and height affect the maximum thrust augmentation ratio attainable. A small amount of cross flow at the inlet increased the maximum thrust augmentation. The alternating primary nozzle injection angle arrangement did not increase the maximum thrust augmentation above that which was obtained using uniform primary nozzle injection angles. Diffuser blowing or suction did not provide an improvement in the maximum thrust augmentation above that which was obtained without diffuser boundary layer control. Finally, at low primary nozzle exit velocities, thrust augmentation increase as the nozzles were moved out along the inlet surface. The increase in thrust augmentation is attributed to the ability of the flow to remain attached to the inlet surface at low primary nozzle exit velocities thereby increasing the ejector effective mixing chamber length. (Author).
Download or read book Paper written by and published by . This book was released on 1984 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of Flow Mixing on Thrust Ejection Efficiency written by Donald J Morfitt (Jr) and published by . This book was released on 1988 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study was to determine the effect flow mixing has on the thrust augmentation of an ejector. The experimental studies were divided into four phases. The four phases were baseline verification, a nozzle tip inclination study, a primary flow pulsing study, and a study of the quality of the ejector. The baseline verification study showed thrust augmentation is dependent upon the injection angle and height of the primary nozzles. The nozzle tip inclination study investigated the effects of having the tips inclined from the inlet surface of the ejector. The nozzle tips were inclined in four different configurations. The different configurations established a baseline or attempted to promote flow mixing and swirling. Theses. (mjm).
Download or read book Experiments on High Speed Ejectors written by and published by . This book was released on 198? with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental studies were conducted to investigate the flow and the performance of thrust augmenting ejectors for flight mach numbers in the range of 0.5 to 0.8, primary air stagnation pressures up to 107 psig (738 kPa), and primary air stagnation temperatures up to 1250 F (677 C). The experiment verified the existence of the second solution ejector flow, where the flow after complete mixing is supersonic. Thrust augmentation in excess of 1.2 was demonstrated for both hot and cold primary jets. The experimental ejector performed better than the corresponding theoretical optimal first solution ejector, where the mixed flow is subsonic. Further studies are required to realize the full potential of the second solution ejector. Keywords: Thrust augmentation; Jet mixing flow; Supersonic flow; Subsonic flight; Transonic flight. (EDC).
