scholarly journals Mixing efficiency of hydrogen jet through multi lobe-injectors at scramjet engine: A numerical study

2021 ◽  
pp. 107293
Author(s):  
Peixi Guo ◽  
Xiaowei Li ◽  
Nidal H. Abu-Hamdeh ◽  
Rashad A.R. Bantan
Keyword(s):  
Numerical Study ◽  
Mixing Efficiency ◽  
Scramjet Engine

scholarly journals Richtmyer-Meshkov Instability Induced Mixing Enhancement in the Scramjet Combustor with a Central Strut

2014 ◽  
Vol 6 ◽  
pp. 614189 ◽  
Author(s):  
Qingchun Yang ◽  
Juntao Chang ◽  
Wen Bao
Keyword(s):  
High Temperature ◽  
Numerical Method ◽  
Chemical Reactions ◽  
Numerical Study ◽  
Numerical Results ◽  
Mixing Efficiency ◽  
Mixing Enhancement ◽  
Scramjet Combustor ◽  
Ordinary Temperature ◽  
Scramjet Engine

Experimental and numerical study of Richtmyer-Meshkov instability (RMI) induced mixing enhancement has been conducted in a liquid-fueled scramjet engine with a central strut. To generate the RMI in the scramjet engine, transverse high temperature jets are employed downstream the strut injector. Compared to the transverse ordinary temperature jet, the jet penetration into the supersonic airstream of high temperature jet increases by 60%. The numerical results indicate that the RMI phenomenon markedly enhances the mixing efficiency (up to 43%), which is necessary to initiate the chemical reactions. Ground experiments were carried out in the combustor, which verify the numerical method from the perspective of wall pressures of the combustor. In particular, the experiment results indicate that the RMI can benefit flame-holding due to the mixing enhancement.

scholarly journals A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs

2021 ◽  
Vol 11 (8) ◽  
pp. 3404
Author(s):  
Majid Hejazian ◽  
Eugeniu Balaur ◽  
Brian Abbey
Keyword(s):  
Molecular Dynamics ◽  
Flow Rate ◽  
Numerical Study ◽  
Three Dimensional ◽  
Microfluidic Devices ◽  
Liquid Jets ◽  
Mixing Efficiency ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Time Required

Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.

Simulation of Two Designs of Micro-Mixers With Enhanced Advection Mechanisms

2011 ◽  
Author(s):  
S. A. Kazemi ◽  
M. Passandideh-Fard ◽  
J. Esmaeelpanah
Keyword(s):  
Numerical Study ◽  
Control Volume ◽  
Numerical Technique ◽  
Chaotic Advection ◽  
Mixing Efficiency ◽  
Mixing Length ◽  
Surface Development ◽  
Mixer Design ◽  
Gas Liquid Flow ◽  
Micro Mixer

In this paper, a numerical study of two new designs of passive micro-mixers based on chaotic advection is presented. The advection phenomenon in a T-shaped micro-mixer is enhanced using a segmented gas-liquid flow; and a peripheral/axial mixing mechanism. The simulations are performed for two non-reactive miscible gases: oxygen and methanol. The numerical model employed for this study is based on the solution of the physical governing equations namely the continuity, momentum, species transport and an equation to track the free surface development. The equations are discretized using a control volume numerical technique. The distribution of the species concentration within the domain is calculated based on which a mixing intensity factor is introduced. This factor is then used as a criterion for the mixing length. In the first micro-mixer design with a drop injection mechanism for a typical condition, the mixing length is reduced by nearly 15%. Compared to that of a simple T-shaped micro-mixer with the same flow rates, the two gases interface area is increased in axisymmetric micro-mixer leading to an increase of the mixing efficiency and a reduction of the mixing length. Also, the effects of the baffles height and span on the mixing efficiency and length in axisymmetric micro-mixer are studied. Having baffles in the channel can substantially decrease the mixing length.

scholarly journals Uncertainty Analysis of Mixing Efficiency Variation in Passive Micromixers due to Geometric Tolerances

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Irina Stanciu
Keyword(s):  
Simulation Model ◽  
Numerical Study ◽  
Geometric Parameters ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Probabilistic Simulation ◽  
Geometric Tolerances ◽  
The Monte Carlo Method ◽  
Key Factor ◽  
Geometric Layout

The geometric layout is the key factor for enhancing the efficiency of the fluid mixing in passive micromixers. Therefore, by adjusting the geometric design and by controlling the geometric parameters, one can enhance the mixing process. However, through any fabrication process, the geometric parameters present slight, inherent variation from the designed values than might affect the performance of the micromixer. This paper proposes a numerical study on the influence of the unavoidable geometric tolerances on the mixing efficiency in passive micromixers. A probabilistic simulation model, based on the Monte Carlo method, is developed and implemented for this purpose. An uncertainty simulation model shows that significant deviations from the deterministic design can appear due to small variations in the geometric parameters values and demonstrates how a more realistic mixing performance can be estimated.

Overview of Fuel Injection Techniques for Scramjet Engines

2011 ◽  
Author(s):  
Wei Huang ◽  
Zhen-guo Wang ◽  
Shi-bin Luo ◽  
Jun Liu ◽  
Zhi-xun Xia ◽  
...  
Keyword(s):  
Fuel Injection ◽  
Mixing Efficiency ◽  
Injection Technique ◽  
Ongoing Research ◽  
Hypersonic Propulsion ◽  
Flame Holder ◽  
Flow Field Characteristics ◽  
Injection Techniques ◽  
Scramjet Engine ◽  
Scramjet Engines

As one of the most promising hypersonic propulsion systems for hypersonic vehicles, the scramjet engine has drawn an ever increasing attention of researchers worldwide. At present, one of the most important issues to be dealt with is how to improve the fuel penetration and mixing efficiency and make the flame stable in supersonic flows. Further, how to reduce the structural weight of the engines is an urgent issue that needs to be considered. The ongoing research efforts on fuel injection techniques in the scramjet engine are described, mainly the cavity flame holder, the backward facing step, the strut injection and the cantilevered ramp injection, and the flow field characteristics and research efforts related to these fuel injection techniques are summarized and compared. Finally, a promising fuel injection technique is discussed, namely a combination of different injection techniques, and the combination of the cantilevered ramp injector and the cavity flame holder is proposed. This is because it can not only stabilize the flame, but also shorten the length of the combustor, thus lighten the weight of the scramjet engines.

Numerical study on micromixers with smart-rhombic structure

2018 ◽  
Vol 32 (27) ◽  
pp. 1850301 ◽  
Author(s):  
Jiajia Xu ◽  
Xueye Chen ◽  
Yanlin Liu ◽  
Zhen Yao
Keyword(s):  
Numerical Simulation ◽  
High Throughput ◽  
Numerical Study ◽  
Considerable Effect ◽  
Geometric Parameters ◽  
Channel Width ◽  
Variable Method ◽  
Mixing Efficiency ◽  
Width Ratio ◽  
Chaotic Convection

In this paper, we have designed a rhombic microchannel plane micromixer (RMPM). The RMPM uses the principle of converging and diverging to improve the mixing efficiency. We improved the mixing efficiency by changing the rhombic angles and the rhombic channel width ratios. The influence of geometric parameters on mixing efficiency is analyzed by control of the variable method. Through the analysis of the numerical simulation, the RMPM can help increase the chaotic convection between different concentrations of fluids. The results of the study show that the rhombic angle and the width ratio of a microchannel can have a considerable effect on the mixing efficiency. The micromixer can be potentially useful in the future applications of rapid and high throughput mixing.

Numerical study of thermal choking process in a model scramjet engine

2000 ◽  
Author(s):  
Guee-Won Moon ◽  
In-Seuck Jeung ◽  
Jeong-Yeol Choi
Keyword(s):  
Numerical Study ◽  
Scramjet Engine
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