The Design and Performance of Two-Dimensional, Curved Diffusers: Part I—Exposition of Method and Part II—Experiment, Evaluation of Method, and Conclusions

1967 ◽  
Vol 89 (4) ◽  
pp. 715-731 ◽  
Author(s):  
C. J. Sagi ◽  
J. P. Johnston
Keyword(s):  
Flow Regime ◽  
Outer Wall ◽  
Center Line ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Wall Potential ◽  
Straight Wall ◽  
Throat Width ◽  
Flow Pressure ◽  
And Performance

A procedure for the design of two-dimensional, curved diffusers is developed and evaluated through comparisons with flow regime and performance data. As input to the method, the inner and outer-wall potential-flow pressure distributions are specified as combinations of straight-wall diffuser pressure distributions. The diffuser shape is calculated using the method of Stanitz. In Part II criteria are established for choosing desirable inner and outer-wall pressure distributions. These criteria are based on systematic performance and flow regime tests carried out on curved diffusers with inner-wall length to throat width ratios between 4 and 10, area ratios between 1.5 and 2.1, and turning angles between 30 and 90 deg. The procedure yields diffusers of higher performance than circular-arc center-line diffusers.

Performance and Design of Straight, Two-Dimensional Diffusers

1967 ◽  
Vol 89 (1) ◽  
pp. 141-150 ◽  
Author(s):  
L. R. Reneau ◽  
J. P. Johnston ◽  
S. J. Kline
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Flow Characteristics ◽  
Performance Data ◽  
Center Line ◽  
Two Dimensional ◽  
Rational Basis ◽  
Primary Flow ◽  
Wide Range ◽  
And Performance

Performance data and flow characteristics for subsonic, two-dimensional, straight center line diffusers are presented. The four primary flow regimes which can occur are described and presented as functions of overall diffuser geometry. The performance of both stalled and unstalled diffusers is mapped for a wide range of geometries and inlet boundary layer thicknesses. An understanding of the relationships between flow regime and performance leads to a rational basis for diffuser design. The important maxima of performance and their location on the performance maps are presented. Both the range of data and correlations of optima of performance are extended beyond previous results.

Effects of Wall Shape on Flow Regimes and Performance in Straight, Two-Dimensional Diffusers

1967 ◽  
Vol 89 (1) ◽  
pp. 151-159 ◽  
Author(s):  
J. J. Carlson ◽  
J. P. Johnston ◽  
C. J. Sagi
Keyword(s):  
Flow Regime ◽  
Performance Prediction ◽  
Prediction Method ◽  
Flow Regimes ◽  
Two Dimensional ◽  
Simple Class ◽  
And Performance

Three diffuser sets (N/W1, held constant in each set) were built and tested for performance and flow regime over a range of total area ratios, AR, which yielded unstalled and stalled flows. At each AR and N/W1, a simple class of convex-inward (trumpet-shaped), straight, and convex-outward (bell-shaped) wall shapes were tested. It is concluded that there is little advantage to be gained by contouring the walls of two-dimensional diffusers. A corollary result shows that the performance prediction method of reference [1] gives good results for unstalled diffusers.

The Departure from Equilibrium of Turbulent Boundary Layers

1968 ◽  
Vol 19 (1) ◽  
pp. 1-19 ◽  
Author(s):  
H. McDonald
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Kinetic Energy ◽  
Stress Distribution ◽  
Boundary Layers ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Momentum Integral ◽  
State Examination

SummaryRecently two authors, Nash and Goldberg, have suggested, intuitively, that the rate at which the shear stress distribution in an incompressible, two-dimensional, turbulent boundary layer would return to its equilibrium value is directly proportional to the extent of the departure from the equilibrium state. Examination of the behaviour of the integral properties of the boundary layer supports this hypothesis. In the present paper a relationship similar to the suggestion of Nash and Goldberg is derived from the local balance of the kinetic energy of the turbulence. Coupling this simple derived relationship to the boundary layer momentum and moment-of-momentum integral equations results in quite accurate predictions of the behaviour of non-equilibrium turbulent boundary layers in arbitrary adverse (given) pressure distributions.

Relationship Between Unsteady Flow, Pressure Fluctuations, and Noise in a Centrifugal Pump—Part B: Effects of Blade-Tongue Interactions

1995 ◽  
Vol 117 (1) ◽  
pp. 30-35 ◽  
Author(s):  
S. Chu ◽  
R. Dong ◽  
J. Katz
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Pressure Difference ◽  
Pressure Fluctuations ◽  
Primary Sources ◽  
Pressure Measurements ◽  
Local Pressure ◽  
Pressure Distributions ◽  
Flow Pressure ◽  
Tip Of The Tongue

Maps of pressure distributions computed using PDV data, combined with noise and local pressure measurements, are used for identifying primary sources of noise in a centrifugal pump. In the vicinity of the impeller pressure minima occur around the blade and near a vortex train generated as a result of non-uniform outflux from the impeller. The pressure everywhere also varies depending on the orientation of the impeller relative to the tongue. Noise peaks are generated when the pressure difference across the tongue is maximum, probably due to tongue oscillations, and when the wake impinges on the tip of the tongue.

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.

Loss Characteristics of Orifices and Nozzles

1978 ◽  
Vol 100 (3) ◽  
pp. 299-307 ◽  
Author(s):  
S. H. Alvi ◽  
K. Sridharan ◽  
N. S. Lakshmana Rao
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Discharge Coefficient ◽  
Critical Reynolds Number ◽  
Reynolds Numbers ◽  
Center Line ◽  
Laminar Regime ◽  
Variation Of Parameters ◽  
Turbulent Flow Regime

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.

Flow Fields in a Two-Dimensional Diffuser With Extraction of Fluid on the Diverging Walls

1972 ◽  
Vol 94 (3) ◽  
pp. 226-232
Author(s):  
D. O. Rockwell
Keyword(s):  
Experimental Verification ◽  
Static Pressure ◽  
Flow Fields ◽  
Hydrogen Bubble ◽  
Two Dimensional ◽  
Stagnation Region ◽  
Pressure Distributions

A theory is developed to describe the inviscid core in two-dimensional unstalled diffusers with suction (extraction) on the diverging walls. Experimental wall static pressure distributions and streamline patterns agree well with those predicted theoretically. Under appropriate extraction conditions, a stagnation region is located downstream of the diverging wall extraction station. Experimental verification of the streamline patterns and of the location of this stagnation region was achieved via hydrogen bubble visualization. In addition, the possible stall conditions, which result if improper extraction is employed, are described qualitatively.

Study on Numerical Simulation and Performance of the Secondary Throttle Choke Used in the Oil Field

2013 ◽  
Vol 712-715 ◽  
pp. 1201-1204
Author(s):  
Hai Feng Zhao ◽  
Yan Xu
Keyword(s):  
Numerical Simulation ◽  
Pressure Change ◽  
Simulation Method ◽  
Differential Pressure ◽  
Oil Field ◽  
Pressure Curve ◽  
Flow Pressure ◽  
Flow Changes ◽  
And Performance ◽  
Main Factor

The numerical simulation method is adopted to calculate the flow field of the secondary throttle choke used in the oil field. The relationships among the flow of the secondary throttle choke, differential pressure and diameters are studied. The results of numerical simulation coincide with the experiment values, which verify that the method is correct. The results show that the flow increases with the increasing of differential pressure of the throttle choke at both ends, but the increment of the flow gradually decreases. The structure could maintain the flow not to change basically when differential pressure change in a certain scope. When the throttle diameter turns out to be small, the flow decreases, and flow-pressure curve gradually becomes aclinic. Compared with the first-class throttle diameter, the second-class throttle diameter is the main factor which effects flow changes.

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