A comparison of numerical and experimental results for unsteady flow associated with jet noise

1994 ◽  
Author(s):  
James Scott
Keyword(s):  
Unsteady Flow ◽  
Jet Noise ◽  
Experimental Results

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.

EVALUATION OF SUBSONIC INFLOW TREATMENTS FOR UNSTEADY JET FLOW

1999 ◽  
Vol 07 (03) ◽  
pp. 147-160 ◽  
Author(s):  
REDA R. MANKBADI ◽  
AMR. A. ALI
Keyword(s):  
Mach Number ◽  
Unsteady Flow ◽  
Linear Approximation ◽  
Acoustic Field ◽  
Linear Prediction ◽  
Jet Noise ◽  
Validity Range ◽  
Radiated Sound ◽  
Unsteady Jet ◽  
Subsonic Jet

Linearized Euler simulations of the unsteady flow of a subsonic jet and its associated acoustic field are presented in this paper. Various subsonic inflow treatments are evaluated. Some of these treatments have been found to produce reflections at the inflow while others are reflection-free. Results are then presented for the effect of Mach number on the radiated sound. It is shown that as the Mach number increases the source becomes noncompact and the directivity is characterized by a well-defined peak. By comparing the linear prediction to the experimental results, validity range of linear approximation for subsonic jet noise is assessed.

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.

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