A Theoretical Analysis of the Viscous Flow in a Narrowly Spaced Radial Diffuser

1957 ◽  
Vol 24 (1) ◽  
pp. 9-15
Author(s):  
Henry W. Woolard
Keyword(s):  
Turbulent Flow ◽  
Viscous Flow ◽  
Plane Surface ◽  
Flow Analysis ◽  
Theoretical Method ◽  
Radial Pressure ◽  
Pressure Distributions ◽  
Disk Valve ◽  
Experimental Pressure ◽  
Good Agreement

Abstract A theoretical method for calculating the radial pressure distribution for laminar viscous flow in a narrowly spaced radial diffuser having arbitrarily shaped walls deviating only moderately from a plane surface is developed. The analysis as it stands is also directly applicable to turbulent flow in the initial inlet region of a diffuser. Additional work is necessary to obtain a complete turbulent-flow analysis. Pressure distributions calculated by the laminar-flow theory show reasonably good agreement with the limited experimental pressure distributions available at the time of the analysis. Fairly good agreement also is obtained for the performance of a disk-valve element.

Effect of Solid Particles on Turbine Performance

1976 ◽  
Vol 98 (1) ◽  
pp. 47-52 ◽  
Author(s):  
W. Tabakoff ◽  
W. Hosny ◽  
A. Hamed
Keyword(s):  
Pressure Distribution ◽  
Gas Flow ◽  
Theoretical Method ◽  
Solid Particles ◽  
Injection System ◽  
Particle Injection ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Experimental Pressure ◽  
Good Agreement

A theoretical method was developed for predicting the pressure distribution over a blade in cascade for a compressible flow with solid particles. Experimental results were obtained from a cascade wind tunnel equipped with a solid particle injection system. Good agreement was noted between the theoretical and experimental pressure distribution. The change in pressure due to the particles gives reduction in the force on the blades. The presence of solid particles in air-breathing engine gas flow changes the turbine performance. The overall turbine efficiency decreases as a result of the introduction of solid particles. The performance experiment was performed on a two-stage velocity-compounded turbine.

Two-dimensional flow of a compressible fluid past given curved obstacles with infinite wakes

1955 ◽  
Vol 227 (1170) ◽  
pp. 367-386 ◽  
Keyword(s):  
Flow Separation ◽  
Subsonic Flow ◽  
Constant Pressure ◽  
Boundary Layer Separation ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Infinite Extent ◽  
Two Dimensional Flow ◽  
Experimental Pressure ◽  
Good Agreement

This paper extends in a number of ways the classical Helmholtz theory of incompressible flow about obstacles behind which are constant-pressure cavities or ‘bubbles’ of infinite extent. The theory given in the paper applies to compressible subsonic flow about given curved obstacles with bubble pressures varying down the wake. As an example the flow is calculated past a circular cylinder for a number of points of flow separation and Mach numbers. When the points of flow separation are the same as those found experimentally, the theoretical and experimental pressure distributions over the cylinder are in good agreement. It is shown that the point of flow separation for ‘proper’ cavitation is almost coincident with the point found experimentally for laminar boundary-layer separation.

Flow Behavior Around Stayvanes and Guidevanes of a Francis Turbine

1996 ◽  
Vol 118 (1) ◽  
pp. 110-115 ◽  
Author(s):  
Toshiaki Suzuki ◽  
Tomotatsu Nagafuji ◽  
Hiroshi Komiya ◽  
Takako Shimada ◽  
Toshio Kobayashi ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Francis Turbine ◽  
Good Prediction ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Pressure Distributions

The three-dimensional computation of steady and incompressible internal flows is of interest in numerical simulations of turbomachinery, and such simulations are currently under investigation, from inviscid to viscous flow analyses. First, surface pressure distributions have been measured for the stayvanes and the guidevanes of a Francis turbine. They are presented to verify the numerical results. Second, both inviscid and viscous three-dimensional flow analyses have been made, so as to predict the flow behavior in the same domain. Comparison of the measured pressure distributions to the predicted pressure distributions has been made to study the usefulness of the present simulations. It can be pointed out that a global analysis which includes a runner flow passage, except runner blades, is necessary to predict the three-dimensional flow characteristics and that inviscid flow analysis has the capability of good prediction for flow without separation. Viscous flow analysis gives similar results, though it is necessary to investigate further the improvement of prediction accuracy. Flow characteristics around the stayvanes and the guidevanes are also discussed.

Some Experiments at Low Speed on Compressor Cascades

1967 ◽  
Vol 89 (3) ◽  
pp. 427-436 ◽  
Author(s):  
D. Pollard ◽  
J. P. Gostelow
Keyword(s):  
Axial Velocity ◽  
Velocity Ratio ◽  
Turbulence Level ◽  
Low Speed ◽  
Pressure Distributions ◽  
Blade Row ◽  
Testing Techniques ◽  
Almost All ◽  
Experimental Pressure ◽  
Good Agreement

Some results of recent work on low-speed cascade tunnels are described. Preliminary investigations, directed toward the analysis and improvement of the airflow and testing techniques, revealed that, when porous sidewall suction was employed, almost all change in axial velocity occurred within the blade row. Variation of axial velocity ratio, aspect ratio, Reynolds number, and turbulence level for one particular cascade facilitated an explanation of differences between the results of early British and American cascade tests. More recently, work has involved cascade tests on an analytically derived cascade. Good agreement was obtained between theoretical and experimental pressure distributions and profile boundary layers.

scholarly journals The Use of De-Swirl Nozzles to Reduce the Pressure Drop in a Rotating Cavity With a Radial Inflow

1989 ◽  
Author(s):  
P. R. Farthing ◽  
J. W. Chew ◽  
J. M. Owen
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Outer Part ◽  
Radial Pressure ◽  
Angular Speed ◽  
Pressure Distributions ◽  
Rotating Cavity ◽  
Predicted Values ◽  
Momentum Integral ◽  
Good Agreement

A combined theoretical and experimental study is described in which de-swirl nozzles were used to reduce the radial pressure drop in a rotating cavity with a radial inflow of air. The nozzles, which were attached to the outer part of the cavity, were angled such that the angular speed of the air at inlet could be in the opposite direction to that of the cavity. Solutions of the momentum-integral equations were used to predict the resulting radial distributions of pressure throughout the cavity. Flow visualization was used to confirm the flow structure, and transducers attached to one of the rotating discs in the cavity were used to measure the radial pressure distributions. Results are presented for ‘swirl fractions’ (that is, the ratio of the angular speed of the air leaving the nozzles to that of the cavity) in the range −0.4 to + 0.9, and for 0.01 < | CW | Reϕ−0.8 < 0.5, where CW and Reϕ, are the nondimensional flow rate and rotational Reynolds number, respectively. The measured pressures are in good agreement with the predicted values, and the pressure drop across the cavity can be significantly less than that associated with solid-body rotation. The flow rate produced by the pressure drop across the cavity is not unique: there are up to three possible values of flow rate for any given value of pressure drop.

Computer Modeling of a Tire under Cornering Loads

1989 ◽  
Vol 17 (2) ◽  
pp. 86-99 ◽  
Author(s):  
I. Gardner ◽  
M. Theves
Keyword(s):  
Finite Element Analysis ◽  
Geometric Approach ◽  
Lateral Force ◽  
Slip Angle ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Slip Effects ◽  
Improved Accuracy ◽  
Nonlinear Geometric ◽  
Good Agreement

Abstract During a cornering maneuver by a vehicle, high forces are exerted on the tire's footprint and in the contact zone between the tire and the rim. To optimize the design of these components, a method is presented whereby the forces at the tire-rim interface and between the tire and roadway may be predicted using finite element analysis. The cornering tire is modeled quasi-statically using a nonlinear geometric approach, with a lateral force and a slip angle applied to the spindle of the wheel to simulate the cornering loads. These values were obtained experimentally from a force and moment machine. This procedure avoids the need for a costly dynamic analysis. Good agreement was obtained with experimental results for self-aligning torque, giving confidence in the results obtained in the tire footprint and at the rim. The model allows prediction of the geometry and of the pressure distributions in the footprint, since friction and slip effects in this area were considered. The model lends itself to further refinement for improved accuracy and additional applications.

Viscous flow analysis using a parallel unstructured multigrid solver

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 2067-2076
Author(s):  
Dimitri J. Mavriplis
Keyword(s):  
Viscous Flow ◽  
Flow Analysis ◽  
Multigrid Solver

Numerical Prediction of Critical Cavitation Performance in Hydraulic Turbines

2003 ◽  
Author(s):  
Sadao Kurosawa ◽  
Kiyoshi Matsumoto
Keyword(s):  
Flow Model ◽  
Flow Analysis ◽  
Prediction Method ◽  
Hydraulic Turbine ◽  
Francis Turbine ◽  
Two Phase ◽  
Cavitation Performance ◽  
Hydraulic Turbines ◽  
Critical Cavitation ◽  
Good Agreement

In this paper, numerical method for predicting critical cavitation performance in a hydraulic turbine is presented. The prediction method is based on unsteady cavitation flow analysis to use bubble two-phase flow model. The prediction of the critical cavitation performance was carried out for the aixal hydraulic turbine and the francis turbine as a typical examples. Results compared to the experiment showed a good agreement for the volume of cavity and the performance drop off and it was recognized that this method could be used as an engineering tool of a hydraulic turbine development.

Numerical Calculation of the Pressure Distributions on a Rudder Surface

2012 ◽  
Vol 562-564 ◽  
pp. 1172-1176
Author(s):  
Jing Ping Wu ◽  
Shun Huai Chen ◽  
Ji Cheng Xiao
Keyword(s):  
Numerical Calculation ◽  
Density Distribution ◽  
Viscous Flow ◽  
Potential Theory ◽  
Airfoil Surface ◽  
Pressure Coefficients ◽  
Viscosity Effect ◽  
Pressure Distributions ◽  
Structure Strength ◽  
Grid Nodes

This paper numerically calculates the pressure distributions of a rudder of a ship for structure strength design. The sections profile of the rudder is NACA0020 airfoil. The viscous flow is simulated by FLUENT commercial software, while the model and mesh is generated by GAMBIT software. A 2D viscous flow around a NACA0020 airfoil is calculated firstly. Some notices are given here about the magnitude of computing domain, the density distribution and the numbers of grid nodes on the airfoil surface in order to gain better results. Then, based on these experiences, the viscous flow around a 3D rudder is simulated. The calculated pressure coefficients on the rudder’s section are compared with the experiment results and BEM results of the potential theory. At the attack angles and , the three results agree well with each other. However, when the attack angle is , the viscous results from FLUENT give better agreement with the experiment results than the BEM results. This conclusion confirms that the viscosity effect is great in the case of large attack angles.

Theoretical Prediction of Motions of High-Speed Planing Boats in Waves

1978 ◽  
Vol 22 (03) ◽  
pp. 140-169
Author(s):  
Milton Martin
Keyword(s):  
High Speed ◽  
Damping Ratio ◽  
Nonlinear Effects ◽  
Theoretical Method ◽  
Valuable Insight ◽  
Response Characteristics ◽  
Theoretical Predictions ◽  
Response Amplitude Operators ◽  
Phase Angles ◽  
Good Agreement

A theoretical method is derived for predicting the linearized response characteristics of constant deadrise high-speed planing boats in head and following waves. Comparisons of the theoretical predictions of the pitch and heave response amplitude operators and phase angles with existing experimental data show reasonably good agreement for a wide variety of conditions of interest. It appears that nonlinear effects are more severe at a speed to length ratio of 6 than of, say, 4 or less, principally because of the reduction of the damping ratio of the boat with increasing speed, and the consequent increase in motions in the vicinity of the resonant encounter frequency. However, it is concluded that the linear theory can provide a simple and fast means of determining the effect of various parameters such as trim angle, deadrise, loading, and speed on the damping, natural frequency, and linearized response in waves, and that this can furnish valuable insight into the actual boat dynamics, even though the accurate predictions of large motions and peak accelerations would require a nonlinear analysis.

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