Aerodynamically Induced Radial Forces in a Centrifugal Gas Compressor: Part 1—Experimental Measurement

1998 ◽  
Vol 120 (2) ◽  
pp. 383-390 ◽  
Author(s):  
J. J. Moore ◽  
M. B. Flathers
Keyword(s):  
Experimental Measurement ◽  
Operating Conditions ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Radial Forces ◽  
Overall Efficiency ◽  
Improved Performance ◽  
Radial Loading

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing techniquesis employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.

scholarly journals Aerodynamically Induced Radial Forces in a Centrifugal Gas Compressor: Part 1 — Experimental Measurement

1996 ◽  
Author(s):  
J. Jeffrey Moore ◽  
Michael B. Flathers
Keyword(s):  
Experimental Measurement ◽  
Processing Technique ◽  
Operating Conditions ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Pressure Distributions ◽  
Pressure Fields ◽  
Radial Forces ◽  
Improved Performance ◽  
Radial Loading

Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increases with higher pressures and speeds. The results are nondimensionalized allowing the radial loading for different operating conditions to be predicted.

scholarly journals Analyses of Hydrodynamic Radial Forces on Centrifugal Pump Impellers

1988 ◽  
Vol 110 (1) ◽  
pp. 20-28 ◽  
Author(s):  
D. R. Adkins ◽  
C. E. Brennen
Keyword(s):  
Theoretical Model ◽  
Centrifugal Pump ◽  
Substantial Effect ◽  
Operating Conditions ◽  
Pump Impeller ◽  
Pressure Distributions ◽  
Flow Disturbances ◽  
Radial Forces ◽  
Flow Through ◽  
Centrifugal Pump Impeller

Hydrodynamic interactions that occur between a centrifugal pump impeller and a volute are experimentally and theoretically investigated. The theoretical analysis considers the inability of the blades to perfectly guide the flow through the impeller, and also includes a quasi-one dimensional treatment of flow in the volute. Flow disturbances at the impeller discharge and the resulting forces are determined by the theoretical model. The model is then extended to obtain the hydrodynamic force perturbations that are caused by the impeller whirling eccentrically in the volute. Under many operating conditions, these force perturbations were found to be destabilizing. Comparisons are made between the theoretical model and the experimental measurements of pressure distributions and radial forces on the impeller. The theoretical model yields fairly accurate predictions of the radial forces caused by the flow through the impeller. However, it was found that the pressure acting on the front shroud of the impeller has a substantial effect on the destabilizing hydrodynamic forces.

Velocity and Pressure Distributions in the Impeller Passages of Centrifugal Pumps

1980 ◽  
Vol 102 (4) ◽  
pp. 420-426 ◽  
Author(s):  
M. Murakami ◽  
K. Kikuyama ◽  
E. Asakura
Keyword(s):  
Flow Rate ◽  
Potential Flow ◽  
Flow Patterns ◽  
Surface Flow ◽  
Design Flow ◽  
Centrifugal Pumps ◽  
Velocity Measurements ◽  
Pressure Distributions ◽  
Insufficient Number ◽  
Good Agreement

The flow patterns in centrifugal pump impellers with three and seven blades, respectively, were measured using a cylindrical yaw probe and an oil surface flow method. The measured distributions of velocities and pressures for the seven (sufficient number) blade impeller at the design flow rate coincide well with the numerical solution obtained from the theoretical equation based on a potential flow. The flow patterns of the three (insufficient number) blade impeller deviate largely from those of the seven blade impeller both at the design and off-design conditions. The values of the slip factor deduced from the data of velocity measurements in the impeller passage were compared with those calculated by commonly-used formulae, and considerably good agreement was obtained for the seven blade impeller.

scholarly journals Characteristics of Centrifugal Pumps Working in Direct or Reverse Mode: Focus on the Unsteady Radial Thrust

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Anthony Couzinet ◽  
Laurent Gros ◽  
Daniel Pierrat
Keyword(s):  
Numerical Data ◽  
Operating Conditions ◽  
Centrifugal Pumps ◽  
Specific Test ◽  
Pump Operation ◽  
Reverse Mode ◽  
Ansys Cfx ◽  
Test Loop ◽  
Radial Forces ◽  
Radial Thrust

Experimental and numerical investigations have been carried out to study the behaviour of a centrifugal pump operating in direct mode or turbine mode. First of all, the complete characteristics (head, power, and efficiency) were measured experimentally using a specific test loop. The numerical data obtained from a CFD study performed with the ANSYS CFX software and based on steady state and unsteady approaches were compared to the experimental results. The representation in the 4 operating quadrants shows the various operating zones where the head is always positive. Then, the unsteady radial forces were analysed from transient computations. The results obtained for the pump operation are consistent with the literature and extended to the nonnormal operating conditions, namely, for very high flowrate values. The evolution of the radial load during turbine operation is presented for various partial flow operating points.

Radial Forces in a Centrifugal Compressor Equipped With Vaned Diffusers

2009 ◽  
Author(s):  
Ahti Jaatinen ◽  
Jari L. H. Backman ◽  
Teemu Turunen-Saaresti
Keyword(s):  
Centrifugal Compressor ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Design Flow ◽  
Vaneless Diffuser ◽  
Rotating Shaft ◽  
Vaned Diffuser ◽  
Pressure Distributions ◽  
Impeller Outlet ◽  
Radial Forces

A non-uniform pressure distribution in a volute of a centrifugal compressor causes a radial force on the impeller and the rotating shaft. The diffuser preceding the volute determines how the flow field entering to the volute, and affects the radial forces that are caused by the volute towards the impeller. The radial forces were measured for three different vaned diffuser geometries and one vaneless diffuser with a pinch. The force measurements were made for each assembly with the same compressor using active magnetic bearings. The impeller forces were found to be the smallest near the design flow and higher at choke and at stall for all configurations. The radial forces on the impeller were higher with the vaneless diffuser than with the vaned diffuser. The force distributions with the vaned diffusers were uniform and clearly different from those of the vaneless diffuser. In addition, the radial forces were estimated using static pressure distributions measured at the impeller outlet. The radial force determined from the pressure measurements verified the measured forces obtained in the magnetic bearing measurements.

Effects of Return Channel With Splitter Vanes on Performance of Multistage Centrifugal Compressor

2015 ◽  
Author(s):  
Manabu Yagi ◽  
Takahiro Nishioka ◽  
Hiromi Kobayashi ◽  
Hideo Nishida ◽  
Satoru Yamamoto
Keyword(s):  
Centrifugal Compressor ◽  
High Flow ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Coefficient ◽  
Optimum Location ◽  
Trailing Edge ◽  
Overall Efficiency ◽  
Return Channel ◽  
Multistage Centrifugal Compressor

The effects of a return channel with splitter vanes on the performance of a multistage centrifugal compressor were investigated. As a preliminary study, the optimum location of the splitter vanes was numerically examined with the aim of achieving high overall efficiency. The results indicated that the optimum location was the 30% of the normalized pitchwise distance from the suction side of the main vane, with the leading-edge located at a radius ratio to the main vane trailing-edge of 1.77. To investigate the effects of the return channel with and without the optimum splitter vanes on the overall performance, performance tests were carried out using a one-and-half-stage test rig. Three pre-swirl vanes, whose vane angles from the tangential direction at the trailing-edge were 20, 30 and 40° were used to simulate three operating conditions with low, design and high flow coefficients, respectively. The design flow coefficient of the downstream impeller was 0.073 and the peripheral Mach number was 0.87. The test results showed that the return channel with the optimum splitter vanes achieved 11.8% higher overall efficiency at the high flow coefficient with respect to the case without the splitter vanes while maintaining the same efficiency at both low and design flow coefficients. The return channel with the optimum splitter vanes was concluded to be effective for improving the efficiency of a multistage centrifugal compressor.

Compressible Flowfield Characteristics of Butterfly Valves

1989 ◽  
Vol 111 (4) ◽  
pp. 400-407 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Flow Separation ◽  
Pressure Ratio ◽  
Disk Surface ◽  
Surface Flow ◽  
Operating Conditions ◽  
Local Geometry ◽  
Operating Pressure ◽  
Butterfly Valve ◽  
Pressure Distributions ◽  
Flow Separation And Reattachment

The results of an experimental investigation into the flowfield characteristics of butterfly valves under compressible flow operating conditions are reported. The experimental results include Schlieren and surface flow visualizations and flowfield static pressure distributions. Two valve disk shapes have been studied in a planar, two-dimensional test section: a generic biconvex circular arc profile and the midplane cross-section of a prototype butterfly valve. The valve disk angle and operating pressure ratio have also been varied in these experiments. The results demonstrate that under certain conditions of operation the butterfly valve flowfield can be extremely complex with oblique shock waves, expansion fans, and regions of flow separation and reattachment. In addition, the sensitivity of the valve disk surface pressure distributions to the local geometry near the leading and trailing edges and the relation of the aerodynamic torque to flow separation and reattachment on the disk are shown.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

Investigation of Squeeze Film Damper Forces Produced by Circular Centered Orbits

1978 ◽  
Vol 100 (1) ◽  
pp. 15-21 ◽  
Author(s):  
E. Feder ◽  
P. N. Bansal ◽  
A. Blanco
Keyword(s):  
Aircraft Engine ◽  
Analytical Investigation ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Oil Viscosity ◽  
Pressure Transducers ◽  
Pressure Distributions ◽  
Pressure Profiles ◽  
Force Components ◽  
Type Pressure

This paper presents the results of an experimental and analytical investigation of the dynamic forces generated by a squeeze film bearing damper constrained to move in circular centered orbits. These orbits were mechanically produced in a specially designed, end sealed, test rig. Aircraft engine damper geometry and operating conditions were simulated. The effect of journal speed, oil viscosity, inlet pressure, and eccentricity ratio on the damper performance was studied. The pressure distributions about the journal were measured for each test condition by high-response diaphragm-type pressure transducers. These pressure profiles were numerically integrated to determine the force components of the squeeze film. Experimental results were compared to an analysis which is summarized in this paper and included the effects of inlet and cavitation pressures. The “long bearing theory” was found to be reasonably accurate in predicting the shape and magnitude of the pressure distribution. Considerable emphasis was directed to the study of the circumferential pressure distributions between 180 deg and 360 deg since aircraft engine dampers generally operate in this region. For the cavitated film (i.e., pressure distributions less than 360 deg), accurate prediction of the damper forces was found to be critically dependent on the effect of inlet and cavitation pressures.

ELECTRICAL BEHAVIOR OF A DOUBLE SIDED PV SOLAR PANEL

2011 ◽  
Vol 2011 (1) ◽  
pp. 000800-000804
Author(s):  
V. Ganescu ◽  
R. Shoaff ◽  
A. Pascu
Keyword(s):  
Thin Film ◽  
Power Output ◽  
Environmental Variables ◽  
Operating Conditions ◽  
Solar Panel ◽  
Back Side ◽  
Solar Pv ◽  
Electrical Behavior ◽  
Pv Module ◽  
Overall Efficiency

An innovative low power (5W) consumer grade dual face PV solar panel assembly is presented in this research. The authors propose capitalizing indirectly on the shadowed face of a typical solar panel by augmenting the panel’s total active area of exposure (via the panel’s “back side” and respective “deflectors”) and aiming at an increase in the overall efficiency of the assembly. Standard environmental operating conditions were taken into account. No CPV were used. The resulting power output profile of this unit is presented in detail and compared with the output of a single sided “standard” solar PV module configuration. In addition, under similar design and operating environmental variables, the behavior of crystalline cells panels is intended to be contrasted with thin film panels’ as variants of this proposed solution.

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