An experimental investigation on the flow structure and mixture formation of low pressure ratio wall-impinging jets by a natural gas injector

Yu, Jingzhou; Vuorinen, Ville; Hillamo, Harri; Sarjovaara, Teemu; Kaario, Ossi; Larmi, Martti

doi:10.1016/j.jngse.2012.05.003

Cited by 33 publications

(19 citation statements)

References 23 publications

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“…In between the slip lines a train of shock cells forms due to reflection of shocks from the shear layers of the jet. Similarities between the present visualization and previous experimental Schlieren experiments 1,4,6,7,12,13 arise, in particular, from the viewpoint of shock structure-NPR dependency. To our knowledge the effect of NPR on jet structure has not been systematically studied by LES previously but, nevertheless, the present LES compares favorably with the previous "numerical Schlieren" visualization by Munday et al 4 and Dauptain et al 5 in terms of shock patterns (reflection, slip line position, shock cells after the Mach disk).…”

Section: A Steady State Jetssupporting

confidence: 87%

“…Yu et al 13 have explained the flow development stages in highly underexpanded jets: (1) initial delay time due to opening of the solenoid valve or injector needle, (2) flow development in the nozzle and building up of the pressure gradient in the nozzle, and (3) fully developed flow. In particular, stage 2 influences the nozzle exit pressure p 1 and it is usual to observe all the standard jet conditions in practice including subsonic, moderately underexpanded and highly underexpanded flow.…”

Section: E Initial Conditions and Flow Rate In Highly Underexpanded mentioning

confidence: 99%

“…In fact, literature has shown that development of the gas motion outside the barrel shock and jet boundary when z/D < 3 depends on the nozzle configuration (e.g., possible asymmetries) and on the level of turbulence development at the nozzle exit. 1,4,6,7,12,13 For example, Panda et al 7 and Munday et al 4 have reported experiments where almost no visible turbulence was observed at the boundary or outside the barrel shock. We conclude that in reality the growth rate of Görtler instabilities is likely to depend on the turbulence development at the nozzle exit.…”

Section: A Steady State Jetsmentioning

confidence: 99%

“…4 The fuel injection nozzles and jet engine exhaust lie somewhere in between the two extreme cases. 13,14 Also the nozzle operating conditions, nozzle pressure ratio (NPR), depend on the application.…”

Section: Introductionmentioning

confidence: 99%

“…The results are qualitatively compared with planar laser induced fluorescence (PLIF) experiments. 13,14 The organization of the paper is as follows: in Sec. II the numerical method is explained, and in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Large-eddy simulation of highly underexpanded transient gas jets

Vuorinen¹,

Yu²,

Tirunagari³

et al. 2013

Physics of Fluids

160

142

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Large-eddy simulations (LES) based on scale-selective implicit filtering are carried out in order to study the effect of nozzle pressure ratios on the characteristics of highly underexpanded jets. Pressure ratios ranging from 4.5 to 8.5 with Reynolds numbers of the order 75 000-140 000 are considered. The studied configuration agrees well with the classical picture of the structure of highly underexpanded jets. Similarities and differences between simulation and experiments are discussed by comparing the concentration field structures from LES and planar laser induced fluorescence data. The transient stages, leading eventually to the highly underexpanded state, are visualized and investigated in terms of a phase diagram revealing the shock speeds and duration of the transient stages. For the studied nozzle pressure ratio range, the Mach disk dimensions are found to be in good agreement with literature data and experimental observations. It is observed how the nozzle pressure ratio influences the Mach disk width, and thereby the slip line separation, which leads to co-annular jets with inner and outer shear layers at higher pressure ratios. The improved mixing with increasing pressure ratio is demonstrated by the probability density functions of the concentration. The coherent structures downstream of the Mach disk are identified using proper orthogonal decomposition (POD). The structures indicate a helical mode originating from the shear layers of the jet. Despite the relatively low energy content of the dominant POD modes, the frequencies of the POD time coefficients explain the dominant frequencies in the pressure fluctuation spectra. C

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Section: A Steady State Jetssupporting

confidence: 87%

Section: E Initial Conditions and Flow Rate In Highly Underexpanded mentioning

confidence: 99%

Section: A Steady State Jetsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Large-eddy simulation of highly underexpanded transient gas jets

Vuorinen¹,

Yu²,

Tirunagari³

et al. 2013

Physics of Fluids

160

142

View full text Add to dashboard Cite

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Flow Pattern and Mixing Performance of a Dynamic Impinging Stream Reactor

Zhang

Rui

et al. 2023

Chem Eng & Technol

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The mixing process of a dynamic impinging stream reactor was measured by planar laser induced fluorescence. The fluid flow pattern and mixing characteristics were studied under different conditions. The flow field was divided into the following regions by flow pattern: free jet region, impingement region, radial jet region, and radial vortex region. The mixing characteristics were analyzed under different operational conditions. The mixing time first decreased and then increased with increasing nozzle spacing. The mixing time decreased with increasing outlet velocity difference and outlet average velocity, and the optimal working conditions were nozzle spacing L = 4d, where d is nozzle diameter, outlet velocity difference vd = 1 m s−1, and outlet average velocity vp = 1.7 m s−1.

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