Ejector performance at high temperatures and pressures

Quinn, B.

doi:10.2514/3.44561

Cited by 33 publications

(8 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this region, the variation of C p along the duct shows two different slopes which switch at about X'/D = 6Q. Similar behavior can be observed in the measurements by Quinn 15 for an axisymmetric ejector and Bernal and Sarohia 16 for a twodimensional ejector. On inspecting the velocity profiles in these two regions as measured by Bernal and Sarohia, it may be suggested that the change in pressure gradient is a result of the jet flow reaching the duct walls.…”

Section: Surface Pressure Measurementssupporting

confidence: 71%

“…18 It is found that the step sizes between the stages are approximately equal. Similar observations made by Quinn 11 ' 15 in his experiments on an underexpanded axisymmetric jet ejector showed that each of the frequency stages corresponded to one of the duct modes. With this in mind, the duct modes were calculated using a two-dimensional wave equation with appropriate boundary conditions assuming no flow in the duct.…”

Section: Screech Tone Characteristicssupporting

confidence: 70%

“…4, the average of the six C Pl , denoted as C Pl , is plotted against the jet pressure ratio R. Also included in the figure is the solution of an invisid one-dimensional compressible ejectory theory following Quinn. 15 Care has to be taken in making the comparison between the experiment and the theory for the present investigation due to the complex model configuration. It is noted that the primary nozzle was placed about two nozzle widths upstream from the entrance of the constant area mixing duct while the theory assumed no such offset.…”

Section: Surface Pressure Measurementsmentioning

confidence: 99%

“…Due to the limitations of the test facility and instrumentation, the total thrust of the ejector and the flow velocity inside the duct were not measured. Surface pressures were measured on the four walls of the ejector shroud for pressure ratios up to 4.4 and five duct widths (W/D = [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. A typical distribution of the pressure coefficient along the walls of the ejector for a width ratio of 20 and at a pressure ratio of 3.4 is shown in Fig.…”

Section: Surface Pressure Measurementsmentioning

confidence: 99%

See 3 more Smart Citations

Mixing of an underexpanded rectangular jet ejector

Hsia

Krothapalli

Baganoff

1988

Journal of Propulsion and Power

View full text Add to dashboard Cite

An experimental investigation was carried out on a rectangular ejector (constant area mixing duct) with an underexpanded rectangular jet as the primary flow. From the wall static pressure measurements, the ejector performance was found to show irregular variations with the primary jet pressure. Hot-wire measurements, together with schlieren photographs, showed that better performance was obtained when the flow was well mixed. The well-mixed flow was found when the screech tone Strouhal number was in the 0.11-0.14 range, which agrees with the most unstable Strouhal number of the free underexpanded rectangular jet. By incorporating a phase-locked technique with shlieren flow visualization, we were able to photograph standing waves excited by the screech tones inside the ejector mixing duct. The interactions between the jet flow and the screech tones were studied using this flow visualization technique. Nomenclature= cross-sectional area of primary nozzle = cross-sectional area of mixing duct = (p-P a )/Pa> pressure coefficient = C p at the entrance of the mixing duct = average of six C^ measured = 5.0 mm, nozzle width (short dimension) = discrete tone frequency = 70.0 mm, height of mixing duct = 50.0 mm, nozzle length (long dimension) = surface static pressure = jet total pressure = ambient pressure =Po / Pa> J et pressure ratio =f*D/U e , Strouhal number = mean velocity = jet exit velocity = mixing duct width = Cartesian coordinates

show abstract

Section: Surface Pressure Measurementssupporting

confidence: 71%

Section: Screech Tone Characteristicssupporting

confidence: 70%

Section: Surface Pressure Measurementsmentioning

confidence: 99%

Section: Surface Pressure Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Mixing of an underexpanded rectangular jet ejector

Hsia

Krothapalli

Baganoff

1988

Journal of Propulsion and Power

View full text Add to dashboard Cite

show abstract

“…By entraining the surrounding ambient air with the primary exhaust flow and directing it into the ejector, the momentum of the engine exhaust flow is increased, leading to the generation of a larger system thrust force [12]. The theory and application of ejectors with regard to a steady primary flow are well established [13,14]. In this type of situation, the secondary flow is entrained primarily through viscous shear mixing [15,16].…”

Section: Introductionmentioning

confidence: 99%

Study on the Operation of Pulse-Detonation Engine-Driven Ejectors

Glaser¹,

Caldwell²,

Gutmark³

et al. 2008

Journal of Propulsion and Power

View full text Add to dashboard Cite

Experimental studies were performed to improve the understanding of the operation of ejector augmenters driven by a pulse-detonation engine. The research employs an H 2 -air pulse-detonation engine at an operating frequency of 30 Hz. Static pressure was measured along the interior surface of the ejector, including the inlet and exhaust sections. Thrust augmentation provided by the ejector was calculated by integration of the static pressure measured along the ejector geometry. The computed thrust augmentation was in good agreement with that obtained from direct thrust measurements. Both straight and diverging ejectors were investigated. The diverging ejector pressure distribution shows that the diverging section acts as a subsonic diffuser and has a tremendous impact on the behavior of the inlet entrainment flow. Static pressure data were also collected for various ejector axial positions. These data supported the thrust augmentation trends found through direct thrust measurements. Specifically, the optimum axial placement was found to be downstream of the pulse-detonation engine near x=D PDE 2, whereas upstream placements tend to result in decreasing thrust augmentation. To provide a better explanation of the observed performance trends, shadowgraph images of the detonation wave and trailing vortex interacting with the ejector inlet were obtained. Nomenclature D EJECT = ejector diameter, cm D PDE = detonation tube diameter, cm DR = ejector-to-PDE diameter ratio ff = fill fraction L EJECT = ejector length, cm L EXHST = exhaust-section length, cm L STRT = intermediate straight-section length, cm T PDE = PDE-system thrust with no ejector installed, N T PDE EJECT = PDE-system thrust with ejector installed, N x = ejector axial position, cm = thrust augmentation, %

show abstract