Performance of Low-Aspect-Ratio Diffusers With Fully Developed Turbulent Inlet Flows: Part I—Some Experimental Results

1973 ◽  
Vol 95 (3) ◽  
pp. 385-392 ◽  
Author(s):  
O. J. McMillan ◽  
J. P. Johnston
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
Boundary Layers ◽  
High Aspect Ratio ◽  
Total Pressure ◽  
Turbulent Boundary Layers ◽  
Two Dimensional ◽  
Low Aspect Ratio ◽  
Performance Curves ◽  
Existing Data

An experimental investigation of the effects of incompressible, fully developed, turbulent inlet flow on the performance of straight, two-dimensional rectangular diffusers of low aspect ratio is presented. Results presented include flow regime information, performance curves, and total-pressure loss data for a series of diffusers of moderate non dimensional length and low aspect ratio. The results are compared to existing data and correlations and important differences are noted between the diffusers of this study and diffusers of high aspect ratio with thin to moderately thick turbulent boundary layers at inlet.

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.

Experimental investigation on tilt stabilizing effect of external toroidal field in low aspect ratio tokamak

1997 ◽  
Vol 4 (2) ◽  
pp. 315-322 ◽  
Author(s):  
A. Morita ◽  
Y. Ono ◽  
M. Katsurai ◽  
M. Yamada ◽  
S. Yoshikawa
Keyword(s):  
Experimental Investigation ◽  
Aspect Ratio ◽  
Toroidal Field ◽  
Low Aspect Ratio ◽  
Stabilizing Effect

Influence of Circumferential Inflow Distortion on the Performance of a Low Speed, High Aspect Ratio Contra Rotating Axial Fan

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Chetan Mistry ◽  
A. M. Pradeep
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Rotational Speed ◽  
Total Pressure ◽  
Flow Behavior ◽  
Axial Fan ◽  
Low Speed ◽  
Overall Performance ◽  
Design Speed ◽  
Inflow Conditions

The influence of circumferential inflow distorted on the performance and flow behavior of a high aspect ratio, low speed contra rotating fan is reported in this paper. The total pressure at the inlet is artificially distorted by means of 90 deg mesh sector with a porosity of 0.70. The performance of the contra rotating fan was studied under different speed combinations of the two rotors under clean and distorted inflow conditions. Detailed flow analyses were conducted under design and off-design conditions. In order to understand the effect of distortion and its extent, the distortion sector was rotated circumferentially at intervals of 15 deg to cover the entire annulus. Detailed measurements of the total pressure, velocity components, and flow angles were carried out at the inlet of the first rotor, between the two rotors, and at the exit of the second rotor. The study reveals a few interesting aspects on the effect of inflow distortion on the performance of a contra-rotating stage. For the design speed combination and lower rotational speed of rotor-2, a reduction in the overall operating range with a shift of the peak pressure point towards higher mass flow rate, was observed. It is observed that the effect of inflow distortion at the inlet of rotor-1 gets transferred in the direction of rotor-1 rotation and spreads across the entire annulus. The opposite sense of rotation of rotor-2 causes the distortion effect to get transferred in the direction of rotation of rotor-2 with an associated reduction in the total pressure near the hub. It is observed that a higher rotational speed of the second rotor has a beneficial effect on the overall performance due to the strong suction by generated higher rotational speed of rotor-2.

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