Qualitative comparison between numerical and experimental results of unsteady flow in a radial diffuser pump

2007 ◽  
Vol 10 (4) ◽  
pp. 349-357 ◽  
Author(s):  
J. Feng ◽  
F. -K. Benra ◽  
H. J. Dohmen
Keyword(s):  
Unsteady Flow ◽  
Experimental Results ◽  
Qualitative Comparison

ON THE STATIC DIELECTRIC CONSTANT OF DIPOLAR SOLIDS

1951 ◽  
Vol 29 (2) ◽  
pp. 163-173 ◽  
Author(s):  
J. H. Simpson
Keyword(s):  
Dielectric Constant ◽  
General Formula ◽  
Short Range ◽  
Nearest Neighbors ◽  
Experimental Results ◽  
Static Dielectric Constant ◽  
Sharp Transition ◽  
Qualitative Comparison ◽  
Dipolar Molecules ◽  
Range Type

An application of Fröhlich's general formula for the static dielectric constant is made to a material having a cubic arrangement of dipolar molecules, each of which has two equilibrium positions 180° apart and ordering forces of the short range type which tend to make nearest neighbors antiparallel. It is shown that such a model cannot lead to a sharp transition in dielectric constant unless changes in lattice dimensions occur. Qualitative comparison with certain experimental results is made.

Periodically Unsteady Flow in a Single-Blade Centrifugal Pump: Numerical and Experimental Results

2005 ◽  
Author(s):  
F.-K. Benra ◽  
H. J. Dohmen ◽  
M. Sommer
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Sewage Water ◽  
Numerical Results ◽  
Experimental Results ◽  
Time Dependent ◽  
Pump Operation ◽  
Wide Range ◽  
Operating Points

The composition of sewage water with partially large portions of fibers and solids requires a special pump design, in order to avoid operational disturbances by clogging. In most applications for sewage water transport, single-stage pumps with single-blade impellers are used. With this special impeller geometry largest flow channels can be realized. So fibers and solids up to an appropriate size can be transported by the pump. This minimum impeller blade number however brings disadvantages for pump operation. The development of a pressure and a suction surface of the blade gives an asymmetric pressure distribution at the perimeter of the rotor outlet and a periodically unsteady flow field arises. In a numerical approach the time accurate flow in a single-blade centrifugal pump has been calculated by solving the 3-dimensional time dependent Reynolds averaged Navier-Stokes equations (URANS) in a wide range of pump operation. The investigation of the flow included all details between suction flange and pressure flange of the pump. The numerical results show a strong dependence from impeller position for all flow parameters. For the investigated operating points strong vortices have been obtained at particular impeller positions. Experimental results have been used to verify the numerical results of time dependent flow in the single-blade pump. The computed flow field has been compared to results which were obtained from optical measurements of flow velocities by Particle Image Velocimetry at different impeller positions. A very good qualitative agreement between measurements and calculations has been obtained for all investigated operating points.

Unsteady Flow Within Centrifugal Compressor Channels Under Rotating Stall and Surge

1992 ◽  
Vol 114 (2) ◽  
pp. 312-320 ◽  
Author(s):  
S. Mizuki ◽  
Y. Oosawa
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Experimental Results ◽  
Vaneless Diffuser ◽  
Lumped Parameter ◽  
Lumped Parameters ◽  
Parameter Theory ◽  
Unsteady Behavior

Unsteady flow patterns throughout a centrifugal compressor system during the rotating stall and the surge were measured experimentally. Various kinds of unsteady behavior of the flow appeared both continuously and suddenly as the flow rate decreased. The part-span stall, the full-span stall, the mild and deep stalls, and the deep surge appeared clearly. The fluctuations caused by the full-span stall were seen even during surge and affected the flow within the scroll through the vaneless diffuser. The experimental results were compared with those computed by the lumped parameter theory. Good agreements between them were obtained when appropriate values were selected for the lumped parameters.

Unsteady Flow Within Centrifugal Compressor Channels Under Rotating Stall and Surge

1991 ◽  
Author(s):  
Shimpei Mizuki ◽  
Yoshimi Oosawa
Keyword(s):  
Unsteady Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Flow Patterns ◽  
Rotating Stall ◽  
Experimental Results ◽  
Vaneless Diffuser ◽  
Lumped Parameter ◽  
Lumped Parameters ◽  
Parameter Theory

Unsteady flow patterns throughout a centrifugal compressor system during the rotating stall and the surge were measured experimentally. Various kinds of unsteady behaviors of the flow appeared both continuously and suddenly as the flow rate decreased. The part-span stall, the full-span stall, the mild and the deep stalls and the deep surge appeared clearly. The fluctuations caused by the full-span stall were seen even during the surge and affected the flow within the scroll through the vaneless diffuser. The experimental results were compared with those computed by the lumped parameter theory. The good agreements between them were obtained when the appropriate values were selected for the lumped parameters.

Unsteady Flow in Diffusers

1994 ◽  
Vol 116 (4) ◽  
pp. 842-847 ◽  
Author(s):  
A. H. M. Kwong ◽  
A. P. Dowling
Keyword(s):  
Unsteady Flow ◽  
Experimental Results ◽  
Pressure Recovery ◽  
Optimum Pressure ◽  
Crucial Effect ◽  
Good Agreement

The flow in a diffuser is unsteady in the range of optimum pressure recovery; diffusers can therefore be a major source of noise in pipework systems. A theory is developed to predict the frequency of this noise and good agreement with experimental results, for both conical and rectangular diffusers, is demonstrated. The acoustics of the duct to which a diffuser is connected are found to have a crucial effect on the unsteady flow within the diffuser, a point which has been overlooked previously in the literature. Once this is recognized, it is possible to reconcile experimental results for air and water diffusers.

Numerical predictions of ship motions at high forward speed

1991 ◽  
Vol 334 (1634) ◽  
pp. 241-252 ◽  
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Steady Flow ◽  
Added Mass ◽  
Numerical Results ◽  
Experimental Results ◽  
Ship Motions ◽  
Forward Speed ◽  
Numerical Predictions

A theory for ship motions at high forward speed is presented. The theory includes interaction between the steady and unsteady flow field. Numerical results for the steady flow and added mass and damping are compared with experimental results.

scholarly journals Research on the Crushing Process of PELE Casing Material Based on the Crack-Softening Algorithm and Stochastic Failure Algorithm

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1561 ◽  
Author(s):  
Liangliang Ding ◽  
Jingyuan Zhou ◽  
Wenhui Tang ◽  
Xianwen Ran ◽  
Ye Cheng
Keyword(s):  
Coincidence Degree ◽  
Experimental Results ◽  
Analysis Software ◽  
Element Analysis ◽  
Qualitative Comparison ◽  
Engineering Research ◽  
Comparison Results ◽  
The Finite Element Analysis ◽  
Simulation Results ◽  
Two Parameters

In order to more realistically reflect the penetrating and crushing process of a PELE (Penetration with Enhanced Lateral Efficiency) projectile, the stochastic failure algorithm and crack-softening algorithm were added to the corresponding material in this paper. According to the theoretical analysis of the two algorithms, the material failure parameters (stochastic constant γ, fracture energy Gf, and tensile strength σT) were determined. Then, four sets of simulation conditions ((a) no crack softening, (b) no stochastic failure, (c) no crack softening and no stochastic failure, and (d) crack softening and stochastic failure) were designed to qualitatively describe the influences of the failure algorithms, which were simulated by the finite element analysis software AUTODYN. The qualitative comparison results indicate that the simulation results after adding the two algorithms were closer to the actual situation. Finally, ten groups of simulation conditions were designed to quantitatively analyze the coincidence degree between the simulation results and the experimental results by means of two parameters: the residual velocity of the projectile and the maximum radial velocity of fragments. The results show that the simulation results coincide well with the experimental results and the errors were small. Therefore, the ideas proposed in this paper are scientific, and the conclusions obtained can provide guidance for engineering research.

Sign in / Sign up

Export Citation Format

Share Document