A Three Dimensional Density Field Measurement of Transonic Flow From a Square Nozzle Using Holographic Interferometry

1977 ◽  
Vol 99 (4) ◽  
pp. 737-743 ◽  
Author(s):  
L. T. Clark ◽  
D. C. Koepp ◽  
J. J. Thykkuttathil
Keyword(s):  
Holographic Interferometry ◽  
Transonic Flow ◽  
Ambient Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Density Field ◽  
Technical Improvement ◽  
Potential Core ◽  
Core Part ◽  
Accurate Experimental Data

The three dimensional static density field was measured for transonic flow from a square nozzle using holographic interferometry. These measurements are presented in order to show the efficiency of this method for obtaining accurate experimental data of transonic flows. The accuracy of the measurement was estimated by operating the nozzle at a pressure ratio of 1.89 where the flow should expand to the ambient pressure with no afterexpansion effects. The standard deviation in the static density was approximately 1 percent over the isentropic (potential core) part of the flow. Data are also presented for a pressure ratio of 2.14 where afterexpansion effects are important. The method described represents a significant technical improvement in practical interferometry.

Quantitative Determination of Three-Dimensional Density Field by Holographic Interferometry

AIAA Journal ◽  
1975 ◽  
Vol 13 (7) ◽  
pp. 841-842 ◽  
Author(s):  
Tse-Fou Zien ◽  
William C. Ragsdale ◽  
W. Charles Spring
Keyword(s):  
Quantitative Determination ◽  
Holographic Interferometry ◽  
Three Dimensional ◽  
Density Field

Finite Fringe Holographic Interferometry Applied to a Right Circular Cone at Angle of Attack

1972 ◽  
Vol 39 (4) ◽  
pp. 897-903 ◽  
Author(s):  
R. C. Jagota ◽  
D. J. Collins
Keyword(s):  
Holographic Interferometry ◽  
Present Report ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Density Field ◽  
Circular Cone ◽  
Governing Equations ◽  
Wind Tunnel Experiments ◽  
Three Dimensional Flow ◽  
Half Angle

The successful application of holography to the study of three-dimensional flow fields due to phase objects has been reported in the literature. The present report extends this technique to the study of density fields around opaque bodies as would normally be encountered in wind tunnel experiments. The density field around a 10-deg half-angle cone at 0 and 10-deg angle of attack has been investigated by means of the finite fringe holographic interferometry. The three-dimensional density field obtained from the reduction of the interferograms was found to agree with that obtained from an analytical solution of the governing equations.

Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES

2012 ◽  
Author(s):  
Adra Benhacine ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar ◽  
Nabil Kharoua
Keyword(s):  
Convex Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Scale Model ◽  
Wall Jet ◽  
Potential Core ◽  
Flat Surfaces ◽  
Free Jet ◽  
Eddy Simulation

A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

Preparation of mesoporous crack-free Sb-SnO2 xerogels through ambient-pressure drying and its application as three-dimensional electrode

2018 ◽  
Vol 86 (2) ◽  
pp. 479-492 ◽  
Author(s):  
Siqi Liu ◽  
Xiezhen Zhou ◽  
Weiqing Han ◽  
Jiansheng Li ◽  
Xiuyun Sun ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Three Dimensional ◽  
Ambient Pressure Drying

Automatic Three-Dimensional Optimisation of a Modern Tandem Compressor Vane

2014 ◽  
Author(s):  
R. C. Schlaps ◽  
S. Shahpar ◽  
V. Gümmer
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Trust Region ◽  
Automatic Generation ◽  
Navier Stokes ◽  
Design Parameters ◽  
High Fidelity ◽  
Stall Margin ◽  
Design Choice ◽  
Multipoint Approximation

In order to increase the performance of a modern gas turbine, compressors are required to provide higher pressure ratio and avoid incurring higher losses. The tandem aerofoil has the potential to achieve a higher blade loading in combination with lower losses compared to single vanes. The main reason for this is due to the fact that a new boundary layer is generated on the second blade surface and the turning can be achieved with smaller separation occurring. The lift split between the two vanes with respect to the overall turning is an important design choice. In this paper an automated three-dimensional optimisation of a highly loaded compressor stator is presented. For optimisation a novel methodology based on the Multipoint Approximation Method (MAM) is used. MAM makes use of an automatic design of experiments, response surface modelling and a trust region to represent the design space. The CFD solutions are obtained with the high-fidelity 3D Navier-Stokes solver HYDRA. In order to increase the stage performance the 3D shape of the tandem vane is modified changing both the front and rear aerofoils. Moreover the relative location of the two aerofoils is controlled modifying the axial and tangential relative positions. It is shown that the novel optimisation methodology is able to cope with a large number of design parameters and produce designs which performs better than its single vane counterpart in terms of efficiency and numerical stall margin. One of the key challenges in producing an automatic optimisation process has been the automatic generation of high-fidelity computational meshes. The multi block-structured, high-fidelity meshing tool PADRAM is enhanced to cope with the tandem blade topologies. The wakes of each aerofoil is properly resolved and the interaction and the mixing of the front aerofoil wake and the second tandem vane are adequately resolved.

Effect of Vaned Diffuser on a Modified Turbocharger Centrifugal Compressor Performance

2014 ◽  
Vol 663 ◽  
pp. 347-353
Author(s):  
Layth H. Jawad ◽  
Shahrir Abdullah ◽  
Zulkifli R. ◽  
Wan Mohd Faizal Wan Mahmood
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Width Ratio ◽  
Outlet Section ◽  
Suction Surface ◽  
Vaned Diffuser ◽  
Minimum Width

A numerical study that was made in a three-dimensional flow, carried out in a modified centrifugal compressor, having vaned diffuser stage, used as an automotive turbo charger. In order to study the influence of vaned diffuser meridional outlet section with a different width ratio of the modified centrifugal compressor. Moreover, the performance of the centrifugal compressor was dependent on the proper matching between the compressor impeller along the vaned diffuser. The aerodynamic characteristics were compared under different meridional width ratio. In addition, the velocity vectors in diffuser flow passages, and the secondary flow in cross-section near the outlet of diffuser were analysed in detail under different meridional width ratio. Another aim of this research was to study and simulate the effect of vaned diffuser on the performance of a centrifugal compressor. The simulation was undertaken using commercial software so-called ANSYS CFX, to predict numerically the performance charachteristics. The results were generated from CFD and were analysed for better understanding of the fluid flow through centrifugal compressor stage and as a result of the minimum width ratio the flow in diffuser passage tends to be uniformity. Moreover, the backflow and vortex near the pressure surface disappear, and the vortex and detachment near the suction surface decrease. Conclusively, it was observed that the efficiency was increased and both the total pressure ratio and static pressure for minimum width ratio are increased.

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