Inlet and Diffuser Effects on Thrust Augmenting Ejectors PDF Download
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Author: S. G. Reznick
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
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.
Author: S. G. Reznick
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
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.
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 524
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Book Description
Author: Generoso C. Uhuad
Publisher:
ISBN:
Category :
Languages : en
Pages : 115
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Book Description
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).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 78
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Book Description
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.
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781731496843
Category : Science
Languages : en
Pages : 170
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Book Description
A method for predicting transient thrust augmenting ejector characteristics is presented. The analysis blends classic self-similar turbulent jet descriptions with a control volume mixing region discretization to solicit transient effects in a new way. Division of the ejector into an inlet, diffuser, and mixing region corresponds with the assumption of viscous-dominated phenomenon in the latter. Inlet and diffuser analyses are simplified by a quasi-steady analysis, justified by the assumptions that pressure is the forcing function in those regions. Details of the theoretical foundation, the solution algorithm, and sample calculations are given. Drummond, Colin K. COMPUTATIONAL FLUID DYNAMICS; COMPUTERIZED SIMULATION; EJECTORS; FINITE VOLUME METHOD; MATHEMATICAL MODELS; THRUST AUGMENTATION; TURBULENT JETS; UNSTEADY FLOW; ALGORITHMS; INLET FLOW; PREDICTION ANALYSIS TECHNIQUES; REAL TIME OPERATION...
Author: Wendell S. Hertzelle
Publisher:
ISBN: 9781423568032
Category :
Languages : en
Pages : 92
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Book Description
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.
Author: Paul Allen Van
Publisher:
ISBN:
Category :
Languages : en
Pages : 118
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Book Description
Author: Tsze C. Tai
Publisher:
ISBN:
Category : Jet propulsion
Languages : en
Pages : 31
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Book Description
Recent advances in jet ejectors operating under static conditions have produced high thrust augmentation that is feasible for application to V/STOL flight. However, because of (a) loss in augmentation in duct flow, (b) ramjet effect, and (c) space limitations, high performance and compactness are required in the design of thrust-augmenting ejectors for V/STOL aircraft. An analytical inverse approach is presented in which the pressure distribution along the diffuser wall of an ejector is defined for a given entrance flow condition and the contour of the desired diffuser wall is determined by using a finite difference technique. The prescribed pressure distribution is first optimized by a modified Stratford criterion for incipient separation of turbulent boundary layers; this optimization makes it applicable to compressible two-dimensional and axisymmetric flows.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 61
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Book Description
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.
Author: Lockheed-Georgia Company
Publisher:
ISBN:
Category : Ejector pumps
Languages : en
Pages : 230
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Book Description
An investigation was conducted to determine the jet thrust augmentation under static conditions for rectangular parallel-divergent wall ejector configurations with multiple primary nozzles. The effect of various geometrical and flow parameters were investigated in order to provide design information. Parameters investigated included the ratio of the ejector exit area to the primary nozzle area, the diffuser angle, the mixing section length, the primary nozzle position, the entrance radius, the number of primary nozzle rows, and the primary nozzle pressure ratio and temperature ratio. The test results are generalized to obtain curves relating the augmentation factor to ejector geometry and flow parameters over a wide range of ejector exit to primary nozzle area ratios. (Author).
