The Flow Around Surface-Mounted, Prismatic Obstacles Placed in a Fully Developed Channel Flow (Data Bank Contribution)

1993 ◽  
Vol 115 (1) ◽  
pp. 85-92 ◽  
Author(s):  
R. Martinuzzi ◽  
C. Tropea
Keyword(s):  
Channel Flow ◽  
Static Pressure ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Data Bank ◽  
Pressure Measurements ◽  
Two Dimensional ◽  
Middle Region ◽  
Visualization Techniques ◽  
Separating Flows

The flow field around surface-mounted, prismatic obstacles with different spanwise dimensions was investigated using the crystal violet, oil-film and laser-sheet visualization techniques as well as by static pressure measurements. The aim of this study is to highlight the fundamental differences between nominally two-dimensional and fully three-dimensional obstacle flows. All experiments were performed in a fully developed channel flow. The Reynolds number, based on the height of the channel, lay between 8 × 104 and 1.2 × 105. Results show that the middle region of the wake is nominally two-dimensional for width-to-height ratios (W/H) greater than 6. The separated region in front of wider obstacles is characterized by the appearance of a quasi-regular distribution of saddle and nodal points on the forward face of the obstacles. These three-dimensional effects are considered to be inherent to such separating flows with stagnation.

Three-dimensional flow in cavities

1963 ◽  
Vol 16 (4) ◽  
pp. 620-632 ◽  
Author(s):  
D. J. Maull ◽  
L. F. East
Keyword(s):  
Static Pressure ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Large Span ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Oil Flow ◽  
Two Dimensional Flow

The flow inside rectangular and other cavities in a wall has been investigated at low subsonic velocities using oil flow and surface static-pressure distributions. Evidence has been found of regular three-dimensional flows in cavities with large span-to-chord ratios which would normally be considered to have two-dimensional flow near their centre-lines. The dependence of the steadiness of the flow upon the cavity's span as well as its chord and depth has also been observed.

Numerical and Experimental Investigation of Return Channel Vane Aerodynamics With Two-Dimensional and Three-Dimensional Vanes

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
A. Hildebrandt ◽  
F. Schilling
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Static Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Field Performance ◽  
Two Dimensional ◽  
Flow Angle ◽  
Overall Performance ◽  
Return Channel

The present paper deals with the numerical and experimental investigation of the effect of return channel (RCH) dimensions of a centrifugal compressor stage on the aerodynamic performance. Three different return channel stages were investigated, two stages comprising three-dimensional (3D) return channel blades and one stage comprising two-dimensional (2D) RCH vanes. The analysis was performed regarding both the investigation of overall performance (stage efficiency, RCH total pressure loss coefficient) and detailed flow-field performance. For detailed experimental flow-field investigation at the stage exit, six circumferentially traversed three-hole probes were positioned downstream the return channel exit in order to get two-dimensional flow-field information. Additionally, static pressure wall measurements were taken at the hub and shroud pressure and suction side (SS) of the 2D and 3D return channel blades. The return channel system overall performance was calculated by measurements of the circumferentially averaged 1D flow field downstream the diffuser exit and downstream the stage exit. Dependent on the type of return channel blade, the numerical and experimental results show a significant effect on the flow field overall and detail performance. In general, satisfactory agreement between computational fluid dynamics (CFD)-prediction and test-rig measurements was achieved regarding overall and flow-field performance. In comparison with the measurements, the CFD-calculated stage performance (efficiency and pressure rise coefficient) of all the 3D-RCH stages was slightly overpredicted. Very good agreement between CFD and measurement results was found for the static pressure distribution on the RCH wall surfaces while small CFD-deviations occur in the measured flow angle at the stage exit, dependent on the turbulence model selected.

Visualizing the Bug Distribution Information Available in Software Bug Repositories

2014 ◽  
pp. 48-66
Author(s):  
N. K. Nagwani ◽  
S. Verma
Keyword(s):  
Open Source ◽  
Three Dimensional ◽  
Distribution Patterns ◽  
Two Dimensional ◽  
Software Bugs ◽  
Process Visualization ◽  
Software Information ◽  
Visualization Techniques ◽  
Software Bug ◽  
Bug Repositories

Software repositories contain a wealth of information that can be analyzed for knowledge extraction. Software bug repositories are one such repository that stores the information about the defects identified during the development of software. Information available in software bug repositories like number of bugs priority-wise, component-wise, status-wise, developers-wise, module-wise, summary-terms-wise, can be visualized with the help of two- or three-dimensional graphs. These visualizations help in understanding the bug distribution patterns, software matrices related to the software bugs, and developer information in the bug-fixing process. Visualization techniques are exploited with the help of open source technologies in this chapter to visualize the bug distribution information available in the software bug repositories. Two-dimensional and three-dimensional graphs are generated using java-based open source APIs, namely Jzy3d (Java Easy 3d) and JFreeChart. Android software bug repository is selected for the experimental demonstrations of graphs. The textual bug attribute information is also visualized using frequencies of frequent terms present in it.

Numerical Flow Analysis in a Subsonic Vaned Radial Diffuser With Leading Edge Redesign

1999 ◽  
Vol 121 (1) ◽  
pp. 119-126 ◽  
Author(s):  
E. Casartelli ◽  
A. P. Saxer ◽  
G. Gyarmathy
Keyword(s):  
Static Pressure ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Leading Edge ◽  
Inverse Design ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Characteristic Lines ◽  
Design Software

The flow field in a subsonic vaned radial diffuser of a single-stage centrifugal compressor is numerically investigated using a three-dimensional Navier–Stokes solver (TASCflow) and a two-dimensional analysis and inverse-design software package (MISES). The vane geometry is modified in the leading edge area (two-dimensional blade shaping) using MISES, without changing the diffuser throughflow characteristics. An analysis of the two-dimensional and three-dimensional effects of two redesigns on the flow in each of the diffuser subcomponents is performed in terms of static pressure recovery, total pressure loss production, and secondary flow reduction. The computed characteristic lines are compared with measurements, which confirm the improvement obtained by the leading edge redesign in terms of increased pressure rise and operating range.

Visualizing the Bug Distribution Information Available in Software Bug Repositories

2017 ◽  
pp. 1255-1273
Author(s):  
N. K. Nagwani ◽  
S. Verma
Keyword(s):  
Open Source ◽  
Three Dimensional ◽  
Distribution Patterns ◽  
Two Dimensional ◽  
Software Bugs ◽  
Process Visualization ◽  
Software Information ◽  
Visualization Techniques ◽  
Software Bug ◽  
Bug Repositories

Software repositories contain a wealth of information that can be analyzed for knowledge extraction. Software bug repositories are one such repository that stores the information about the defects identified during the development of software. Information available in software bug repositories like number of bugs priority-wise, component-wise, status-wise, developers-wise, module-wise, summary-terms-wise, can be visualized with the help of two- or three-dimensional graphs. These visualizations help in understanding the bug distribution patterns, software matrices related to the software bugs, and developer information in the bug-fixing process. Visualization techniques are exploited with the help of open source technologies in this chapter to visualize the bug distribution information available in the software bug repositories. Two-dimensional and three-dimensional graphs are generated using java-based open source APIs, namely Jzy3d (Java Easy 3d) and JFreeChart. Android software bug repository is selected for the experimental demonstrations of graphs. The textual bug attribute information is also visualized using frequencies of frequent terms present in it.

Numerical and Experimental Investigation on a Low-Speed Compressor Cascade With Circulation Control

2008 ◽  
Author(s):  
S. Fischer ◽  
H. Saathoff ◽  
R. Radespiel
Keyword(s):  
Wind Tunnel ◽  
Static Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Circulation Control ◽  
Two Dimensional ◽  
Compressor Cascade ◽  
Flow Topology ◽  
Wind Tunnel Tests ◽  
Low Speed

Experimental and numerical results for the flow through a stator cascade with active flow control are discussed. By blowing air through a slot close to the trailing edge of the aerofoils, the deflection angle as well as the static pressure rise in the stator are increased. The aerofoil design is representative for a 1st-stage stator geometry of a multi-stage compressor adapted for low–speed applications. To allow a reasonable transfer of the high-speed results to low-speed wind tunnel conditions, a corresponding cascade geometry was generated applying the Prandtl–Glauert analogy. With this modified cascade numerical simulations and experiments have been conducted at a Reynolds number of 5 · 105. As a reference case two-dimensional flow simulations without circulation control are considered using a Navier–Stokes solver. In the related wind tunnel tests three–dimensional conditions occur in the test rig. Nevertheless five–hole probe measurements in the wake of the blade mid section show a good agreement with the theoretical characteristics. Additional investigation along the whole blade span gives a deeper insight into the flow topology. For design conditions different blowing rates are applied. The wind tunnel tests confirm the positive benefit, which is predicted by two-dimensional calculations. The offset between simulated and measured pressure rise decreases with increasing blowing mass flows due to the reduction of the axial velocity ratio. This result is related to a redistribution of the passage flow which can only be explained in a three–dimensional analysis including the side wall influence. The benefit of the circulation control at varying blowing rates is finally characterized by the efficiency and the static pressure rise per injected energy.

Steady and Unsteady Characteristics of Two Corner Separations in a Decelerating Square Channel Flow

2006 ◽  
Author(s):  
Yoichi Kinoue ◽  
Toshiaki Setoguchi ◽  
Norimasa Shiomi ◽  
Kenji Kaneko
Keyword(s):  
Channel Flow ◽  
Cross Correlation ◽  
Static Pressure ◽  
Three Dimensional ◽  
Side Wall ◽  
Turbulence Level ◽  
Square Channel ◽  
Unsteady Characteristics ◽  
Decelerating Channel Flow ◽  
Peak Value

The three-dimensional separation in a decelerating channel flow generated by the suction through a porous side wall had been investigated experimentally. Unsteady characteristics of two corner separations were especially focused on. The profiles of time averaged static pressure are two-dimensional in the height direction even in the case with large regions of corner separation. The contour of the turbulence level of the mainstream velocity shows two peak values which correspond to two corner separations. The value of cross-correlation gets large negative values without any lag and the value of coherence gets peak value at around 0.5–2 Hz. The corner separations near the top wall and near the bottom wall are not independent and keep coherent structure both with negative value of cross correlation function and with the frequency of around 0.5–2 Hz.

Experimental Investigation of a Three-Dimensional Boundary Layer Flow in the Vicinity of an Upright Wall Mounted Cylinder (Data Bank Contribution)

1992 ◽  
Vol 114 (4) ◽  
pp. 566-576 ◽  
Author(s):  
J. H. Agui ◽  
J. Andreopoulos
Keyword(s):  
Boundary Layer ◽  
Flow Visualization ◽  
Large Scale ◽  
Laser Sheet ◽  
Three Dimensional ◽  
Data Bank ◽  
Separation Point ◽  
Primary Vortex ◽  
Dimensional Boundary ◽  
The Mean

The flow of a three-dimensional boundary layer approaching an upright wall mounted circular cylinder has been experimentally investigated by means of instantaneous flow visualization techniques using a laser sheet and time resolved measurements of the wall pressure, the gradients of which are related to the vorticity flux away from the wall. The mean separation point of the oncoming boundary layer is located on the plane of symmetry, 0.76 and 0.82 diameters upstream of the cylinder for the two investigated Reynolds numbers, based on the cylinder diameter, of 1.0 × 105 and 2.2 × 105, respectively. The present flow visualization studies have shown that there is always a primary vortex present in the flow which induces an eruption of wall fluid. Very often, this eruption results in the formation of counter rotating or mushroom vortices. A secondary vortex further upstream has been observed occasionally. This vortex, as well as the vortices formed by the fast eruption of wall fluid evolve quickly in time and space and therefore cannot be obtained from time-average measurements. The primary vortex consists of several large scale structures which have originated in the oncoming boundary layer and which have acquired substantial additional vorticity. Point measurements indicate that the r.m.s. pressure fluctuations increase as separation is approached and reach a maximum near reattachment. A low degree of space-time correlation and longer integral time scales were also observed downstream of separation. A bimodal probability density function of the fluctuating pressure was observed in the vicinity of the mean separation point, close to the corner region and in the wake of the cylinder. Quasi periodic vortex shedding from the cylinder with a Strouhal number 0.13 was also observed.

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