Optimal Streamwise Vortices Intended for Supersonic Mixing Enhancement

Abstract Non-premixed combustion was implemented in a micro-lobed combustion system, and its influence on combustion was studied using both experiments and simulations. The results show that a micro-lobed burner produces streamwise vortices with intensities that increase with the equivalence ratio of methane to oxygen (Φ). Due to the streamwise vortices and the increment of the contact area between methane and oxygen, the gasses mix well in the micro-lobed burner, giving it a larger OH mass fraction and higher temperatures than the micro-splitter burner. Moreover, the equivalence ratio greatly influences the combustion enhancement from the micro-lobed burner, especially near the burner exit. The maximum temperature difference between the two micro-burners at the Z/D = 0.01 cross section is 171 K, when Φ is 0.6. However, when the mixing enhancement caused by the streamwise vortices disappears, Φ has little influence on the combustion temperature of the micro-lobed burner, especially when Φ ≥ 1. In this case, the maximum temperature variation between the micro-lobed burner and micro-splitter burner remains nearly constant.

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602 Supersonic Mixing Enhancement Using Interaction between Jet and Flexible Rubber Sheets

The Proceedings of Conference of Tokai Branch ◽

10.1299/jsmetokai.2007.56.273 ◽

2007 ◽

Vol 2007.56 (0) ◽

pp. 273-274

Author(s):

Shohei YAMASHITA ◽

Yohei YOSHIDA ◽

Kazuhiko YOKOTA ◽

Motoyuki ITOH ◽

Shinji TAMANO

Keyword(s):

Mixing Enhancement ◽

Supersonic Mixing

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A LES Study on Passive Mixing in Supersonic Shear Layer Flows Considering Effects of Baffle Configuration

Advances in Mechanical Engineering ◽

10.1155/2014/836146 ◽

2014 ◽

Vol 6 ◽

pp. 836146 ◽

Cited By ~ 1

Author(s):

Ren Zhao-Xin ◽

Wang Bing

Keyword(s):

Pressure Loss ◽

Total Pressure ◽

Large Scale ◽

Mixing Layer ◽

Total Pressure Loss ◽

Mixing Efficiency ◽

Mixing Enhancement ◽

Supersonic Mixing ◽

Passive Mixing ◽

Supersonic Mixing Layer

Under the background of dual combustor ramjet (DCR), a numerical investigation of supersonic mixing layer was launched, focused on the mixing enhancement method of applying baffles with different geometric configurations. Large eddy simulation with high order schemes, containing a fifth-order hybrid WENO compact scheme for the convective flux and sixth-order compact one for the viscous flux, was utilized to numerically study the development of the supersonic mixing layer. The supersonic cavity flow was simulated and the cavity configuration could influence the mixing characteristics, since the impingement process of large scale structures formed inside the cavity could raise the vorticity and promote the mixing. The effect of baffle's configurations on the mixing process was analyzed by comparing the flow properties, mixing efficiency, and total pressure loss. The baffle could induce large scale vortexes, promote the mixing layer to lose its stability easily, and then lead to the mixing efficiency enhancement. However, the baffle could increase the total pressure loss. The present investigation could provide guidance for applying new passive mixing enhancement methods for the supersonic mixing.

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Mechanism of supersonic mixing enhancement by a wall-mounted three-dimensional cavity

Acta Astronautica ◽

10.1016/j.actaastro.2021.08.019 ◽

2021 ◽

Vol 188 ◽

pp. 491-504

Author(s):

Masayuki Anyoji ◽

Fujio Akagi ◽

Yu Matsuda ◽

Yasuhiro Egami ◽

Taro Handa

Keyword(s):

Three Dimensional ◽

Mixing Enhancement ◽

Supersonic Mixing

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Experiments of Supersonic Mixing and Combustion Enhancement Using Alternating-Wedge Strut: Part 1 —Effects of Supersonic Streamwise Vortices in a Scramjet Combustor

JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ◽

10.2322/jjsass.50.135 ◽

2002 ◽

Vol 50 (579) ◽

pp. 135-135 ◽

Cited By ~ 2

Author(s):

Tetsuji Sunami ◽

Michael N. Wendt ◽

Michio Nishioka ◽

Atsuo Murakami ◽

Kenji Kudou

Keyword(s):

Streamwise Vortices ◽

Scramjet Combustor ◽

Supersonic Mixing ◽

Combustion Enhancement

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The flow characteristics of a confined square jet with mixing tabs

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1243/0954410981532144 ◽

1998 ◽

Vol 212 (2) ◽

pp. 63-76 ◽

Cited By ~ 1

Author(s):

S C M Yu ◽

Y X Hou ◽

S C Low

Keyword(s):

Flow Characteristics ◽

Side Wall ◽

Laser Doppler Anemometer ◽

Mixing Enhancement ◽

Streamwise Vortices ◽

Streamwise Vorticity ◽

Mean Velocity ◽

Downstream Distance ◽

Two Component ◽

Breadth Ratio

The flow characteristics of a confined square jet with mixing tabs have been determined by measurements obtained using a two-component laser Doppler anemometer at a Reynolds number of 1.026 × 105 (based on the exit hydraulic diameter, DH = 60 mm, and bulk mean velocity, Ur, of the stream at 1.71 m/s). Both tabs of rectangular and triangular shapes are considered with the same height-breadth ratio ( h/b = 1.35) and with their apex leaning downstream. Altogether four tabs have been used, with one tab each located at the centre of each side wall at the exit plane. Each tab is found to produce a dominant pair of counter-rotating streamwise vortices. The combined effects of the four tabs bifurcate the jet into four ‘fingers’, resulting in a significant increase in entrainment at the downstream locations. The strength of the streamwise vorticity generated by the rectangular tabs is some 30 per cent higher than the triangular ones and decays faster with downstream distance. This appears due to a larger tab surface area which creates a larger pressure differential across the rectangular tab than the triangular tab. The region of high turbulent kinetic energy is found firstly at the locations where the streamwise vortices stretch the normal vortices and subsequently at locations where the streamwise vortices break down, resulting in significant mixing enhancement. Finally, the effects of the so-called secondary tabs have also been examined and are found to enhance the mixing further. The orientation of the secondary tabs is, however, crucial for the mixing enhancement to occur.

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