The effect of aspect ratio on isolator performance

Cox-Stouffer, S.; Hagenmaier, Mark A.

doi:10.2514/6.2001-519

Cited by 16 publications

(11 citation statements)

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“…Computations by Cox-Stouffer and Hagenmaier solved the three-dimensional Reynolds-averaged conservation equations for perfect gases with a cell-centered finite volume scheme. 11 The results showed that increasing the aspect ratio lead to a longer shock train with the shocks stabilizing further upstream. The trends agree with experimental results but the numbers were never directly compared.…”

Section: Introductionmentioning

confidence: 94%

Boundary layer separation in a 3D shock train

Klomparens

Gamba

Driscoll

2015

53rd AIAA Aerospace Sciences Meeting

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Schlieren movies and pressure measurements were collected to analyze the quasi-steady state properties of an oblique shock train generated in a Mach 2.75 ducted flow and stabilized by a back-valve. Different values of back pressure (p b ) were considered to generate the shock train. Schlieren movies were processed with an edge detection algorithm to locate the shocks in the first interaction of the shock train. The shock train location was found to have a linear relationship with back pressure. More unsteady motion was found in the case with lower p b . The maximum amplitude of the shock displacement was 0.9H. In most cases, there was a dominant frequency of 145 Hz in both the shock position and speed power spectra. The highest back pressure case showed no dominant peak in the spectra. The average shock location was taken from Schlieren results and compared with pressure measurements. The shock location coincided with the start of the pressure rise and the local peak in the pressure standard deviation. Three-dimensional effects were evident from the comparison of side-and bottom-wall measurements. The side-walls had local maximum in the pressure profile likely due to the thin side-wall boundary layer. Bottom-wall pressure profiles were nearly linear. Finally, the shape of the time-averaged pressure distribution compared well with previous experimental and theoretical results.

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Section: Introductionmentioning

confidence: 94%

Boundary layer separation in a 3D shock train

Klomparens

Gamba

Driscoll

2015

53rd AIAA Aerospace Sciences Meeting

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Section: Model Verification -Reacting Flowmentioning

confidence: 98%

“…At the same time, equation (10) does not explicitly refer to the effects of ignition process or changes in combustion rate. 2 Figure 11 shows the combustion efficiency calculated with equation (10) for all cases. In general, the combustion efficiency increases for all cases with the increase of the axial distance from the point of injection with a rapid increase of the efficiency is seen in the first half of the combustor.…”

Section: Model Verification -Reacting Flowmentioning

confidence: 98%

A three-dimensional computational study of the effect of the inlet conditions on supersonic mixing and combustion

Abdel-Salam

Micklow

2012

Proceedings of the Institution of Mechanical Engineers, Part G:

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In recent years, a significant amount of high-speed combustion research has been directed toward optimization of scramjet combustors, and in particular on the efficiency of fuel-air mixing and reaction taking place in the engine. This article numerically investigates the flow characteristics of a dual-mode scramjet-combustor configuration. Results are presented for a three-dimensional combustor model with a single wall-mounted raised (compression) ramp as a fuel injector. Hydrogen is used as the fuel and is injected through the raised ramp (which has an aspect ratio of 0.5) parallel to the air stream. Vitiated air with different concentrations of H 2 O and CO 2 are used at the inlet boundary. Three equivalence ratios were simulated, 0.25, 0.31, and 0.41. Numerical results are obtained using a finite volume computational fluid dynamics code. Initially, three forms of the two-equation k-" turbulent model were tested: the standard, the RNG, and the realizable with unstructured grids. Final results were obtained with the RNG form of the k-" turbulent model. Results show that the combustion efficiency decreases with the increase of the equivalence ratio. Also, the cases with CO 2 show slightly higher combustion efficiencies.

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“…A further study by Bement et al [11] confirmed that the Waltrup and Billig correlation is also applicable to calculate shock train length in a rectangular isolator by replacing cylinder diameter with duct height of rectangular section, but a discrepancy exist between the predicted curve and experimental data. The difference should be attributed to geometric differences [12][13].…”

Section: Introductionmentioning

confidence: 99%

“…In engine design, the isolator length has to be optimal to minimize the weight and drag of the overall system and fully hold shock train, and therefore it is vital to well understand shock train behavior and accurately calculate shock train length in the isolator under flight conditions. To resolve these issues, numerous investigations [4][5][6][7][8][9][10][11][12][13] have performed to examine the influence of parameters such as the entrance conditions, the exit back pressure ratio and geometric effects. It is found that the occurrence of shock train pattern strongly depends on the upstream Mach number and the boundary layer thickness.…”

Section: Introductionmentioning

confidence: 99%