An Experimental Study of Static Thrust Augmentation Using a 2-D Variable Ejector

An Experimental Study of Static Thrust Augmentation Using a 2-D Variable Ejector
Author: Eli Kedem
Publisher:
Total Pages: 97
Release: 1979
Genre:
ISBN:

A short rectangular throat ejector was constructed and tested to determine the effects of a number of variables on thrust augmentation and mass augmentation. The variables included those associated with geometry (e.g., diffuser length/throat length, diffuser area ratio, diffuser sidewall angle, nozzle angles and positions) and those due to differences in primary mass flow rate distributions among the nozzles. There were two kinds of thrust augmentation that were calculated; the free thrust augmenting ratio and the isentropic thrust augmenting ratio. The free thrust augmenting ratio is the ratio of the ejector's measured thrust to the sum of the nozzles' measured thrust, if each of them were discharged separately to ambient pressure. The isentropic thrust augmenting ratio is the ratio of the ejector's measured thrust to the calculated thrust of the nozzles if discharged isentropically to the ambient pressure. A free thrust augmentating ratio as high as 1.63 and an isentropic thrust augmenting ratio of up to 1.29 were obtained. Mass augmentation which is the ratio of secondary flow to primary flow was in the range of 3.5 to 5. Some conclusions concerning design aspects were drawn also. They include the necessity of 3-D shrouding for the ejector's inlet and exit and the prevention of blowing high velocity air (primary and BLC flow) tangential to the ejector walls. (AUthor).

Masters Theses in the Pure and Applied Sciences

Masters Theses in the Pure and Applied Sciences
Author: W. H. Shafer
Publisher: Springer Science & Business Media
Total Pages: 307
Release: 2013-03-14
Genre: Science
ISBN: 1475757859

Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 24 (thesis year 1979) a total of 10,033 theses titles from 26 Canadian and 215 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work. While Volume 24 reports these submitted in 1979, on occasion, certain universities do report theses submitted in previous years but not reported at the time.

An Experimental Study of a Three-Dimensional Thrust Augmenting Ejector Using Laser Doppler Velocimetry

An Experimental Study of a Three-Dimensional Thrust Augmenting Ejector Using Laser Doppler Velocimetry
Author: National Aeronautics and Space Adm Nasa
Publisher:
Total Pages: 132
Release: 2018-11-17
Genre:
ISBN: 9781731249487

Flow field measurements were obtained in a three-dimensional thrust augmenting ejector using laser Doppler velocimetry and hot wire anemometry. The primary nozzle, segmented into twelve slots of aspect ratio 3.0, was tested at a pressure ratio of 1.15. Results are presented on the mean velocity, turbulence intensity, and Reynolds stress progressions in the mixing chamber of the constant area ejector. The segmented nozzle was found to produce streamwise vortices that may increase the mixing efficiency of the ejector flow field. Compared to free jet results, the jet development is reduced by the presence of the ejector walls. The resulting thrust augmentation ratio of this ejector was also calculated to be 1.34. Storms, Bruce Lowell Unspecified Center EJECTORS; FLOW MEASUREMENT; LASER DOPPLER VELOCIMETERS; REYNOLDS STRESS; THREE DIMENSIONAL FLOW; THRUST AUGMENTATION; TURBULENCE EFFECTS; VORTICES; ASPECT RATIO; EXHAUST VELOCITY; HOT-WIRE ANEMOMETERS; NOZZLE DESIGN; PRESSURE RATIO; V/STOL AIRCRAFT...

Experimental Investigation of a Thrust Augmenting Ejector

Experimental Investigation of a Thrust Augmenting Ejector
Author: Hidayat Wiradimadja
Publisher:
Total Pages: 0
Release: 1985
Genre:
ISBN:

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.

NASA SP.

NASA SP.
Author:
Publisher:
Total Pages: 592
Release: 1988
Genre: Aeronautics
ISBN:

An Experimental Investigation of Two-Dimensional Thrust Augmenting Ejectors

An Experimental Investigation of Two-Dimensional Thrust Augmenting Ejectors
Author: L. Bernal
Publisher:
Total Pages: 104
Release: 1984
Genre:
ISBN:

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.