scholarly journals Theoretical and experimental investigations on aero-optical effect at the second stage of the compressible mixing layer

2014 ◽  
Vol 63 (5) ◽  
pp. 054703
Author(s):  
Gan Cai-Jun ◽  
Li Lang ◽  
Ma Han-Dong ◽  
Xiong Hong-Liang
Keyword(s):  
Mixing Layer ◽  
Experimental Investigations ◽  
Optical Effect ◽  
Compressible Mixing Layer ◽  
Second Stage

scholarly journals Theoretical and experimental investigation on aero-optical effect for a compressible mixing layer

2013 ◽  
Vol 62 (18) ◽  
pp. 184701
Author(s):  
Gan Cai-Jun ◽  
Li Lang ◽  
Ma Han-Dong ◽  
Xiong Hong-Liang
Keyword(s):  
Experimental Investigation ◽  
Mixing Layer ◽  
Optical Effect ◽  
Compressible Mixing Layer

scholarly journals Inviscid spatial stability of a compressible mixing layer. Part 3. Effect of thermodynamics

1991 ◽  
Vol 224 ◽  
pp. 159-175 ◽  
Author(s):  
T. L. Jackson ◽  
C. E. Grosch
Keyword(s):  
Prandtl Number ◽  
Mixing Layer ◽  
Mean Flow ◽  
Temperature Relation ◽  
Compressible Mixing Layer ◽  
Spatial Stability ◽  
Mean Temperature ◽  
The Mean ◽  
The Difference ◽  
The Stability

We report the results of a comprehensive comparative study of the inviscid spatial stability of a parallel compressible mixing layer using various models for the mean flow. The models are (i) the hyperbolic tangent profile for the mean speed and the Crocco relation for the mean temperature, with the Chapman viscosity–temperature relation and a Prandtl number of one; (ii) the Lock profile for the mean speed and the Crocco relation for the mean temperature, with the Chapman viscosity-temperature relation and a Prandtl number of one; and (iii) the similarity solution for the coupled velocity and temperature equations using the Sutherland viscosity–temperature relation and arbitrary but constant Prandtl number. The purpose of this study was to determine the sensitivity of the stability characteristics of the compressible mixing layer to the assumed thermodynamic properties of the fluid. It is shown that the qualitative features of the stability characteristics are quite similar for all models but that there are quantitative differences resulting from the difference in the thermodynamic models. In particular, we show that the stability characteristics are sensitive to the value of the Prandtl number and to a particular value of the temperature ratio across the mixing layer.

An experimental investigation of the effects of compressibility on a turbulent reacting mixing layer

1998 ◽  
Vol 356 ◽  
pp. 25-64 ◽  
Author(s):  
M. F. MILLER ◽  
C. T. BOWMAN ◽  
M. G. MUNGAL
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Structural Changes ◽  
Density Ratio ◽  
Mixing Layer ◽  
Mixing Layers ◽  
Unexpected Result ◽  
Entrainment Ratio ◽  
Plan View ◽  
Compressible Mixing Layer

Experiments were conducted to investigate the effect of compressibility on turbulent reacting mixing layers with moderate heat release. Side- and plan-view visualizations of the reacting mixing layers, which were formed between a high-speed high-temperature vitiated-air stream and a low-speed ambient-temperature hydrogen stream, were obtained using a combined OH/acetone planar laser-induced fluorescence imaging technique. The instantaneous images of OH provide two-dimensional maps of the regions of combustion, and similar images of acetone, which was seeded into the fuel stream, provide maps of the regions of unburned fuel. Two low-compressibility (Mc=0.32, 0.35) reacting mixing layers with differing density ratios and one high-compressibility (Mc=0.70) reacting mixing layer were studied. Higher average acetone signals were measured in the compressible mixing layer than in its low-compressibility counterpart (i.e. same density ratio), indicating a lower entrainment ratio. Additionally, the compressible mixing layer had slightly wider regions of OH and 50% higher OH signals, which was an unexpected result since lowering the entrainment ratio had the opposite effect at low compressibilities. The large-scale structural changes induced by compressibility are believed to be primarily responsible for the difference in the behaviour of the high- and low-compressibility reacting mixing layers. It is proposed that the coexistence of broad regions of OH and high acetone signals is a manifestation of a more biased distribution of mixture compositions in the compressible mixing layer. Other mechanisms through which compressibility can affect the combustion are discussed.

scholarly journals Skew Rolling of Rods from Scrap Rail Heads

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2970 ◽  
Author(s):  
Tomczak ◽  
Pater ◽  
Bulzak
Keyword(s):  
Experimental Tests ◽  
Rolling Process ◽  
Industrial Applications ◽  
Experimental Investigations ◽  
Longitudinal Rolling ◽  
Rolling Mills ◽  
Second Stage ◽  
New Process ◽  
Skew Rolling ◽  
Theoretical Considerations

This paper presents the results of theoretical and experimental investigations of a new process of rolling rods from scrap rail heads. First, the industrial applications of scrap railway rails and methods of their recycling are discussed, and then the concept of two-stage rolling of rods from heads cut off from scrap rails is proposed. In the first stage of the process, a rail head preform was rolled in a hexagonal pass of a longitudinal rolling mill. Then in the second stage, the hexagonal bar was skew rolled into a rod in a helical roll pass. Theoretical considerations were based on finite element numerical modelling. The rolling process was simulated under 3D deformation using Forge NxT v.1.1 software developed by Transvalor Company. Calculations were carried out to determine the material flow kinematics, strength, and thermal parameters of the process and to identify the phenomena that might constrain its implementation. The numerical results were verified in experimental tests, during which preforms and rods were formed from scrap rail heads. The tests were conducted in longitudinal and skew rolling mills. The results indicate that rods can be effectively formed from scrap rail heads in just two steps. Rods obtained using the proposed method can be used as full-featured, semifinished products for the manufacture of various types of machine parts.

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