A Numerical Methodology to Predict Exhaust Plumes of Propulsion Nozzles

1998 ◽  
Vol 120 (3) ◽  
pp. 563-569 ◽  
Author(s):  
F. Nasuti ◽  
R. Niccoli ◽  
M. Onofri
Keyword(s):  
Turbulent Mixing ◽  
Contact Discontinuity ◽  
Mixing Layer ◽  
Computational Grid ◽  
Practical Applications ◽  
Exhaust Plumes ◽  
Validation Tests ◽  
Exhaust Jet ◽  
Nozzle Flows ◽  
Cumbersome Calculation

A simple methodology to simulate the mixing layers that occur between nozzle exhaust jet and the external air is proposed. The method is based on a simplified model of the plume, that replaces the mixing layer with a contact discontinuity surface, thus avoiding the cumbersome calculation of the turbulent mixing of two flows with different chemical composition. The contact discontinuity is numerically treated by an advanced fitting technique, capable of tracking the discontinuity by points floating over the computational grid. The numerical method is discussed and its capability is demonstrated with validation tests, as well as with a discussion of some practical applications for underexpanded nozzle flows.

Wavelet analysis of shearless turbulent mixing layer

2021 ◽  
Vol 33 (2) ◽  
pp. 025109
Author(s):  
T. Matsushima ◽  
K. Nagata ◽  
T. Watanabe
Keyword(s):  
Wavelet Analysis ◽  
Turbulent Mixing ◽  
Mixing Layer ◽  
Turbulent Mixing Layer

scholarly journals Mixing and chemical reactions in a turbulent liquid mixing layer

1986 ◽  
Vol 170 ◽  
pp. 83-112 ◽  
Author(s):  
M. M. Koochesfahani ◽  
P. E. Dimotakis
Keyword(s):  
Reynolds Number ◽  
Gas Phase ◽  
Turbulent Mixing ◽  
High Speed ◽  
High Reynolds Number ◽  
Schmidt Number ◽  
Mixing Layer ◽  
Entrainment Ratio ◽  
High Reynolds ◽  
Mixed Fluid

An experimental investigation of entrainment and mixing in reacting and non-reacting turbulent mixing layers at large Schmidt number is presented. In non-reacting cases, a passive scalar is used to measure the probability density function (p.d.f.) of the composition field. Chemically reacting experiments employ a diffusion-limited acid–base reaction to directly measure the extent of molecular mixing. The measurements make use of laser-induced fluorescence diagnostics and high-speed, real-time digital image-acquisition techniques.Our results show that the vortical structures in the mixing layer initially roll-up with a large excess of fluid from the high-speed stream entrapped in the cores. During the mixing transition, not only does the amount of mixed fluid increase, but its composition also changes. It is found that the range of compositions of the mixed fluid, above the mixing transition and also throughout the transition region, is essentially uniform across the entire transverse extent of the layer. Our measurements indicate that the probability of finding unmixed fluid in the centre of the layer, above the mixing transition, can be as high as 0.45. In addition, the mean concentration of mixed fluid across the layer is found to be approximately constant at a value corresponding to the entrainment ratio. Comparisons with gas-phase data show that the normalized amount of chemical product formed in the liquid layer, at high Reynolds number, is 50% less than the corresponding quantity measured in the gas-phase case. We therefore conclude that Schmidt number plays a role in turbulent mixing of high-Reynolds-number flows.

Time resolved flow-field measurements of a turbulent mixing layer over a rectangular cavity

2010 ◽  
Vol 51 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Shiyao Bian ◽  
James F. Driscoll ◽  
Brian R. Elbing ◽  
Steven L. Ceccio
Keyword(s):  
Flow Field ◽  
Turbulent Mixing ◽  
Mixing Layer ◽  
Field Measurements ◽  
Rectangular Cavity ◽  
Time Resolved ◽  
Turbulent Mixing Layer

scholarly journals Experimental study into the Rayleigh–Taylor turbulent mixing zone heterogeneous structure

2003 ◽  
Vol 21 (3) ◽  
pp. 375-379 ◽  
Author(s):  
Yu.A. KUCHERENKO ◽  
A.P. PYLAEV ◽  
V.D. MURZAKOV ◽  
A.V. BELOMESTNIH ◽  
V.N. POPOV ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Measurement Errors ◽  
Density Ratio ◽  
Mixing Layer ◽  
Light Sheet ◽  
Immiscible Fluids ◽  
Heterogeneous Structure ◽  
Layer System ◽  
Glycerin Solution ◽  
Refractive Index Matching

Experiments conducted on the SOM facility at the Russian Federal Nuclear Center–VNIITF, concerning the turbulent mixing induced by the Rayleigh–Taylor instability in a three-layer system of immiscible liquids are described. The fluids are contained in a small tank 6.4 cm × 5.4 cm × 12 cm, which is accelerated vertically downward by a gas gun. The mixing layer evolution was imaged by seeding one of the fluids with particles and using a bidirectional light sheet method (refractive index matching was used to minimize measurement errors). Experiments were performed for two different accelerations (g = 350 g0 and g = 100 g0, where g0 = 980 cm/s2, and the acceleration decreases with distance traveled), and with aqueous solutions of glycerin and benzene (with density ratio 1.6). The lower, middle, and upper layers were a sodium hyposulfite–glycerin solution, a water–glycerin solution, and benzene, respectively. The glycerin solution was seeded with particles. The principal objective of the experiments was to obtain the distribution of fluid particle sizes arising from the mixing of the immiscible fluids.

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