scholarly journals Analysis of Compressibility Effects and Nonlinear Property Variations in a Supercritical CO2 Mixing Layer

2022 ◽  
Author(s):  
Dhruv Purushotham ◽  
Kyle A. Schau ◽  
Joseph C. Oefelein
Keyword(s):  
Supercritical Co2 ◽  
Mixing Layer ◽  
Nonlinear Property ◽  
Compressibility Effects

Compressibility effects in a turbulent annular mixing layer. Part 1. Turbulence and growth rate

2000 ◽  
Vol 421 ◽  
pp. 229-267 ◽  
Author(s):  
JONATHAN B. FREUND ◽  
SANJIVA K. LELE ◽  
PARVIZ MOIN
Keyword(s):  
Growth Rate ◽  
Mach Number ◽  
Mixing Layer ◽  
Mixing Layers ◽  
Velocity Difference ◽  
Mean Velocity ◽  
The Mean ◽  
Mach Numbers ◽  
High Mach ◽  
Compressibility Effects

This work uses direct numerical simulations of time evolving annular mixing layers, which correspond to the early development of round jets, to study compressibility effects on turbulence in free shear flows. Nine cases were considered with convective Mach numbers ranging from Mc = 0.1 to 1.8 and turbulence Mach numbers reaching as high as Mt = 0.8.Growth rates of the simulated mixing layers are suppressed with increasing Mach number as observed experimentally. Also in accord with experiments, the mean velocity difference across the layer is found to be inadequate for scaling most turbulence statistics. An alternative scaling based on the mean velocity difference across a typical large eddy, whose dimension is determined by two-point spatial correlations, is proposed and validated. Analysis of the budget of the streamwise component of Reynolds stress shows how the new scaling is linked to the observed growth rate suppression. Dilatational contributions to the budget of turbulent kinetic energy are found to increase rapidly with Mach number, but remain small even at Mc = 1.8 despite the fact that shocklets are found at high Mach numbers. Flow visualizations show that at low Mach numbers the mixing region is dominated by large azimuthally correlated rollers whereas at high Mach numbers the flow is dominated by small streamwise oriented structures. An acoustic timescale limitation for supersonically deforming eddies is found to be consistent with the observations and scalings and is offered as a possible explanation for the decrease in transverse lengthscale.

Modelling of Compressibility Effects in Mixing Layer

2002 ◽  
Author(s):  
Bertrand Aupoix
Keyword(s):  
Mixing Layer ◽  
Turbulence Models ◽  
Spreading Rate ◽  
Compressible Turbulence ◽  
Navier Stokes ◽  
Rate Reduction ◽  
Boundary Layer Flows ◽  
Turbulence Effects ◽  
Self Similar ◽  
Compressibility Effects

The ability of turbulence models to predict self-similar mixing layers is investigated. The influence of velocity is well captured but no model reproduces the sensitivity of the mixing layer to density differences. A correction proposed for boundary layer flows hardly affects mixing layer predictions. A correction is proposed but is not satisfactory. At last, compressible turbulence effects are investigated. Without corrections, models cannot predict the spreading rate reduction. Standard corrections predict too weak a reduction. The sonic eddy concept is validated whatever the turbulence model. A form suitable for Navier-Stokes codes is proposed.

Compressibility effects in a reacting mixing layer

1993 ◽  
Author(s):  
M. MILLER ◽  
T. ISLAND ◽  
J. SEITZMAN ◽  
C. BOWMAN ◽  
M.G. MUNGAL ◽  
...  
Keyword(s):  
Mixing Layer ◽  
Compressibility Effects

Toward second-moment closure modelling of compressible shear flows

2013 ◽  
Vol 733 ◽  
pp. 325-369 ◽  
Author(s):  
Carlos A. Gomez ◽  
Sharath S. Girimaji
Keyword(s):  
High Speed ◽  
Evolution Equations ◽  
Thermal Flux ◽  
Mixing Layer ◽  
Layer Growth ◽  
Moment Closure ◽  
Unified Framework ◽  
Second Moment Closure ◽  
Closure Modelling ◽  
Compressibility Effects

AbstractCompressibility profoundly affects many aspects of turbulence in high-speed flows, most notably stability characteristics, anisotropy, kinetic–potential energy interchange and spectral cascade rate. We develop a unified framework for modelling pressure-related compressibility effects by characterizing the role and action of pressure in different speed regimes. Rapid distortion theory is used to examine the physical connection between the various compressibility effects leading to model form suggestions for pressure–strain correlation, pressure–dilatation and dissipation evolution equations. The closure coefficients are established using fixed-point analysis by requiring consistency between model and DNS asymptotic behaviour in compressible homogeneous shear flow. The closure models are employed to compute high-speed mixing layers and boundary layers. The self-similar mixing-layer profile, increased Reynolds stress anisotropy and diminished mixing-layer growth rates with increasing Mach number are all well captured. High-speed boundary-layer results are also adequately replicated even without the use of advanced thermal-flux models or low-Reynolds-number corrections.

Compressibility effects on the structure of supersonic mixing layers: experimental results

1994 ◽  
Vol 259 ◽  
pp. 47-78 ◽  
Author(s):  
S. Barre ◽  
C. Quine ◽  
J. P. Dussauge
Keyword(s):  
Mixing Layer ◽  
Spreading Rate ◽  
Turbulent Friction ◽  
Radiated Noise ◽  
Supersonic Mixing ◽  
Diffusion Scheme ◽  
Supersonic Mixing Layer ◽  
Compressibility Effects ◽  
Supersonic Mixing Layers ◽  
Convective Mach Number

An experiment in a supersonic mixing layer at convective Mach number Mc = 0.62 was performed to study the evolution of a flow from a turbulent boundary layer to a fully developed mixing layer. Turbulence measurements were taken and are interpreted with a diffusion model, which is well adapted to these flows. These measurements show that the level of turbulent friction varies with Mc proportionally to the spread rate. Our measurements appear to be consistent with the spreading rate of the layer and suggest that compressibility does not significantly alter the diffusion scheme at Mc = 0.62. This is also confirmed by a review of the existing data. Moreover, in the present flow, the anisotropy of the turbulent stresses seems to be affected by compressibility. The evolution of the radiated noise shows an increase corresponding to the developed part of the layer. Quantitative assessments of compressibility effects on turbulent quantities are given and are related to modifications in the structure of the flow.

0806 A study of compressibility effects on sound sources in high Mach number mixing layer

2015 ◽  
Vol 2015 (0) ◽  
pp. _0806-1_-_0806-4_
Author(s):  
Daiki TERAKADO ◽  
Taku NONOMURA ◽  
Akira OYAMA ◽  
Kozo FUJII
Keyword(s):  
Mach Number ◽  
Mixing Layer ◽  
Sound Sources ◽  
High Mach Number ◽  
High Mach ◽  
Compressibility Effects

scholarly journals On density effects and large structure in turbulent mixing layers

1974 ◽  
Vol 64 (4) ◽  
pp. 775-816 ◽  
Author(s):  
Garry L. Brown ◽  
Anatol Roshko
Keyword(s):  
Turbulent Mixing ◽  
High Speed ◽  
Density Ratio ◽  
Mixing Layer ◽  
Density Fluctuations ◽  
Large Structure ◽  
Density Effects ◽  
Large Structures ◽  
Different Gases ◽  
Compressibility Effects

Plane turbulent mixing between two streams of different gases (especially nitrogen and helium) was studied in a novel apparatus. Spark shadow pictures showed that, for all ratios of densities in the two streams, the mixing layer is dominated by large coherent structures. High-speed movies showed that these convect at nearly constant speed, and increase their size and spacing discontinuously by amalgamation with neighbouring ones. The pictures and measurements of density fluctuations suggest that turbulent mixing and entrainment is a process of entanglement on the scale of the large structures; some statistical properties of the latter are used to obtain an estimate of entrainment rates. Large changes of the density ratio across the mixing layer were found to have a relatively small effect on the spreading angle; it is concluded that the strong effects, which are observed when one stream is supersonic, are due to compressibility effects, not density effects, as has been generally supposed.

Theoretical Analysis of the Effect of Compressibility and Free-Stream Turbulence on Free-Mixing Turbulent Gas Flows

1976 ◽  
Vol 43 (2) ◽  
pp. 217-221
Author(s):  
B. K. Shivamoggi
Keyword(s):  
High Speed ◽  
Free Stream ◽  
Mixing Layer ◽  
Gas Flows ◽  
Flow Equations ◽  
Free Stream Turbulence ◽  
Gas Streams ◽  
Layer Flow ◽  
Flow Similarity ◽  
Compressibility Effects

A theoretical investigation is made of the effect of compressibility and free-stream turbulence on the mixing-layer flow between high-speed parallel turbulent gas streams. Compressibility effects on turbulence are formulated through suitable phenomenological models. The flow similarity principle is then invoked to analyze the flow equations; the results of which directly reveal the manner in which the compressibility effects and the free-stream turbulence affect the development of the mixing flow.

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