Numerical investigation of the role of hyper-mixers in supersonic mixing

2010 ◽  
Vol 114 (1161) ◽  
pp. 659-672 ◽  
Author(s):  
S. L. N. Desikan ◽  
K. Kumaran ◽  
V. Babu
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Numerical Study ◽  
Mie Scattering ◽  
Stagnation Pressure ◽  
Reacting Flow ◽  
Qualitative Comparison ◽  
Supersonic Mixing ◽  
High Speed Flows

Abstract In this numerical study, the role of hyper-mixers on supersonic mixing is investigated for six different strut configurations. To this end, 3D, compressible, turbulent, non-reacting flow calculations with air as the secondary injectant have been carried out. A qualitative comparison of the predictions with experimental results is made through Schlieren and Mie scattering images. A quantitative evaluation of the predictions is made by comparison with experimentally measured exit stagnation pressure, wall static pressure and the degree of unmixedness. Based on these results, three strut configurations have been selected for carrying out simulations with hydrogen as the injectant. Results from the hydrogen simulations are compared with the predictions using air and also across the strut configurations. The results clearly demonstrate that castellated strut configurations are very effective in enhancing mixing in such high speed flows.

Experimental investigation of the role of struts in high speed mixing

2013 ◽  
Vol 117 (1188) ◽  
pp. 193-211 ◽  
Author(s):  
S. L. N. Desikan ◽  
J. Kurian
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
High Speed ◽  
Static Pressure ◽  
Mie Scattering ◽  
Total Pressure Loss ◽  
Pressure Losses ◽  
Mixing Performance ◽  
Supersonic Mixing

AbstractThis paper presents the experimental results of the role of struts in supersonic mixing. Experiments were carried out with novel strut configurations to show their capabilities on mixing with reasonable total pressure losses. The performances were compared with the Baseline Strut configurations (BSPI and BSNI). The analysis presented includes the mixing quantifications using Mie scattering signature, flow field visualisation, measurement of wall static pressure and the total pressure loss calculations. The results clearly demonstrated that the proposed strut configurations achieved increased mixing (7-8%) compared to BSPI with increase in total pressure loss (2%). On the other hand, when compared with BSNI, the mixing performance was found to be decreased by 6% with reduced total pressure loss (12%).

Factors Affecting the Performance of the Supersonic Parallel Diffuser

1966 ◽  
Vol 8 (1) ◽  
pp. 62-69 ◽  
Author(s):  
B. W. Martin
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Area Ratio ◽  
Stagnation Pressure ◽  
Pressure Recovery ◽  
Cross Sectional ◽  
Factors Affecting ◽  
Single Shock ◽  
Wide Range

Following the work of Baker and Martin (1), this paper provides further information about static pressure recovery in axi-symmetric supersonic parallel diffusers of fixed length and the same upstream generating nozzle when the diffuser cross-sectional area is varied over a wide range. Correlations based on these and associated experiments by Martin and Baker (2) indicate an area ratio for maximum possible static pressure recovery. At breakdown of the single shock, the diffuser stagnation pressure ratio corresponds to that for normal shock pressure recovery, while the outlet Mach number becomes independent of area ratio as the latter increases. The factors which influence the development and stability of the single shock regime are considered in some detail, from which the role of the boundary layer is shown to be predominant.

Numerical Study of Laser-Induced Ignition at high speed flows

2020 ◽  
Author(s):  
Rajib Mahamud ◽  
Albina Tropina ◽  
Richard B. Miles
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Induced Ignition ◽  
High Speed Flows

Numerical Investigation of High Speed Combustion and its Impact on Thermal Structure

2014 ◽  
Author(s):  
Litao Zhang ◽  
Lili Zheng ◽  
Lingyun Hou
Keyword(s):  
Heat Flux ◽  
Thermal Stress ◽  
High Speed ◽  
Thermal Stresses ◽  
Numerical Study ◽  
Thermal Structure ◽  
Great Influence ◽  
Leading Edge ◽  
Reacting Flow ◽  
Fuel Flow

This paper presents numerical study of high-speed combustion and its relationship with thermal stress distribution on a cavity combustion chamber. First, a physical model is established to describe high speed compressible turbulent reacting flow as well as thermal transport in combustor structure. It is then applied to a model combustor with two-staged fuel injections to examine the effects of fuel flow rate and inflow conditions on the heat flux intensity and thermal stress distributions across the thickness of the combustor wall. The result shows that the injection method of the first stage has a great influence on the flow field near the second one, and it affects combustion and heat release distribution inside the combustor. The intensity of heat flux passing through the combustor wall changes along the downstream of the flow, and large thermal stresses are generated in the vicinity of the injector, the leading edge and the trailing edge of the cavity.

scholarly journals Simulating Bluff-Body Flameholders: On the Use of Proper Orthogonal Decomposition for Combustion Dynamics Validation

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Ryan Blanchard ◽  
A. J. Wickersham ◽  
Lin Ma ◽  
Wing Ng ◽  
Uri Vandsburger
Keyword(s):  
Heat Release ◽  
Proper Orthogonal Decomposition ◽  
High Speed ◽  
Bluff Body ◽  
Numerical Study ◽  
Orthogonal Decomposition ◽  
Time Averaging ◽  
Reacting Flow ◽  
Combustion Dynamics ◽  
Proper Orthogonal

Contemporary tools for experimentation and computational modeling of unsteady and reacting flow open new opportunities for engineering insight into dynamic phenomena. In this article, we describe a novel use of proper orthogonal decomposition (POD) for validation of the unsteady heat release of a turbulent premixed flame stabilized by a vee-gutter bluff-body. Large-eddy simulations were conducted for the same geometry and flow conditions as examined in an experimental rig with chemiluminescence measurements obtained with a high-speed camera. In addition to comparing the experiment to the simulation using traditional time-averaging and pointwise statistical techniques, the dynamic modes of each are isolated using proper orthogonal decomposition (POD) and then compared mode-by-mode against each other. The results show good overall agreement between the shapes and magnitudes of the first modes of the measured and simulated data. A numerical study of into the effects of various simulation parameters on these heat release modes showed significant effects on the flame's effective angle but also on the size, shape, and symmetry patterns of the flame's dynamic modes.

Supersonic Flow at Micro-Tube Outlet

2009 ◽  
Author(s):  
Yasuhiro Yoshida ◽  
Chungpyo Hong ◽  
Yutaka Asako ◽  
Koichi Suzuki
Keyword(s):  
Mach Number ◽  
High Speed ◽  
Mach Disk ◽  
Stagnation Pressure ◽  
Experimental Investigations ◽  
Micro Channel ◽  
Expansion Waves ◽  
Channel Outlet ◽  
Sonic Flow

The boundary layer is formed on micro-channel walls and its thickness becomes 0 at the exit of the channel. And, it plays a role of a wall of a converging and diverging nozzle and the flow becomes supersonic at the micro-channel outlet. Then outlet Mach number is beyond unity. This fact is not widely known. Therefore, experimental investigations on behavior of super sonic flow at the outlet of straight micro-tubes whose diameter ranges from 150 to 500 μm are conducted. The stagnation pressure ranges 379 from to 812 kPa. The successive expansion and recompression waves of under-expanded state were visualized by Schlieren method and a high-speed camera. The numerical investigations are also performed for straight micro-tubes with diameter ranging from 50 to 400 μm. Numerical methodology is based on the aribitary-Langrangian-Eulerian (ALE) method. The stagnation pressure was chosen in such a way that the Mach number at the tube outlet ranges from 1.0 to 1.6. The ambient back pressure is fixed at the atmospheric pressure. The flow at the tube outlet change from the over-expanded to the under-expanded state. It is observed that the recompression and expansion waves are alternately formed in downstream of the micro-tube outlet in both experiments and numerical computations. The experimental correlation for the distance from the micro-tube outlet to the Mach disk as a function of pressure at the outlet was proposed for the prediction of outlet pressure of micro-tube in under-expanded.

A NUMERICAL STUDY ON THE PERFORMANCE OF A SUDDEN EXPANSION WITH MULTISTEPS AS A DIFFUSER

2011 ◽  
Vol 03 (04) ◽  
pp. 779-802 ◽  
Author(s):  
D. K. MANDAL ◽  
N. K. MANNA ◽  
S. BANDYOPADHYAY ◽  
B. P. BISWAS ◽  
S. CHAKRABARTI
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Static Pressure ◽  
Numerical Study ◽  
Pressure Rise ◽  
Simple Algorithm ◽  
Stagnation Pressure ◽  
Effective Length ◽  
Sudden Expansion ◽  
Flow Reynolds Number

In this paper, the numerical analysis and performance simulation of a sudden expansion with multisteps viewed as a diffuser have been carried out. The two-dimensional steady differential equations for conservation of mass and momentum have been solved using the SIMPLE algorithm. The Reynolds number is in the range of 20 to 100. In this study, the configurations of plain sudden expansion and sudden expansion with two, three, four and five steps have been considered. An aspect ratio of 2 is fixed for all the computations. The effect of Reynolds number and number of steps on average static pressure, diffuser effectiveness, distance of maximum static pressure rise from throat and average stagnation pressure have been studied in detail. From the study, it is revealed that sudden expansion with multisteps always offers benefits in any Reynolds number (20–100) at aspect ratio of 2 with respect to a plain sudden expansion as far as its effectiveness and stagnation pressure drop are concerned. At lower Reynolds number, effectiveness of the sudden expansion with multisteps offers substantial benefit without much benefit in its performance at higher flow Reynolds number. The effective length of diffuser increases with Reynolds number, while, increase in number of steps does not have much impact on effective length at a particular value of flow Reynolds number.

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