scholarly journals Rotordynamic Forces in Cavitating Inducers

1997 ◽  
Vol 119 (4) ◽  
pp. 768-774 ◽  
Author(s):  
A. Bhattacharyya ◽  
A. J. Acosta ◽  
C. E. Brennen ◽  
T. K. Caughey
Keyword(s):  
Experimental Investigation ◽  
Axial Flow ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Quadratic Functional ◽  
Functional Behavior ◽  
Rotordynamic Forces ◽  
Frequency Ratios

This paper reports an experimental investigation of rotordynamic forces in a whirling axial flow inducer under the influence of cavitation at various flow coefficients. The results show the occurrence of large destabilizing peaks in the force tangential to the whirl orbit for positive whirl frequency ratios. The magnitude of the destabilizing forces increased with a decrease in cavitation number and flow coefficient. The rotordynamic data obtained do not exhibit quadratic functional behavior normally assumed in many rotordynamic models. Consequently, conventional generalized stiffness, damping, and inertia matrices cannot be determined for the inducer. The results demonstrate the complexity of rotordynamic forces and their consequences on stability of axial flow inducers.

Experimental Characterization of the Rotordynamic Forces on Space Rocket Axial Inducers

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Lucio Torre ◽  
Angelo Pasini ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Flow Coefficient ◽  
Test Facility ◽  
Speed Ratio ◽  
Quadratic Functional ◽  
Pump Operation ◽  
Functional Behavior ◽  
Space Rocket ◽  
The Stability ◽  
Rotordynamic Forces

The present paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility (CPRTF) at ALTA S.p.A. aimed at characterizing the rotordynamic forces acting on two different whirling tapered-hub, variable-pitch axial inducers. The forces acting on the impeller have been measured by means of a rotating dynamometer mounted just behind the inducer. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number, and liquid temperature have been investigated. The destabilizing role of cavitation has been confirmed. The experimental results are consistent with previous experimental campaigns documented by the open literature, including the former data published by Caltech researchers. The observed dependence of the tangential and normal components of the rotordynamic force on the whirl-to-rotational speed ratio does not follow the quadratic functional behavior often assumed in the open literature. Rotordynamic forces of large amplitude and destabilizing nature especially occur in the presence of cavitation, potentially compromising the stability of the pump operation.

Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer

2011 ◽  
Author(s):  
Lucio Torre ◽  
Angelo Pasini ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Continuous Spectrum ◽  
Experimental Technique ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Test Facility ◽  
Liquid Temperature ◽  
Qualitative And Quantitative ◽  
Experimental Campaign ◽  
The Stability ◽  
Rotordynamic Forces

The paper illustrates the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.

Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer

2011 ◽  
Vol 133 (12) ◽  
Author(s):  
Angelo Pasini ◽  
Lucio Torre ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Continuous Spectrum ◽  
Experimental Technique ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Test Facility ◽  
Liquid Temperature ◽  
Qualitative And Quantitative ◽  
Experimental Campaign ◽  
The Stability ◽  
Rotordynamic Forces

The paper illustrates the results of an experimental campaign conducted in the Cavitating Pump Rotordynamic Test Facility at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.

Inlet Skew and the Growth of Secondary Losses and Vorticity in a Turbine Cascade

1989 ◽  
Author(s):  
J. A. Walsh ◽  
D. G. Gregory-Smith
Keyword(s):  
Experimental Investigation ◽  
Large Scale ◽  
Transverse Velocity ◽  
Axial Flow ◽  
Turbine Cascade ◽  
Streamwise Vorticity ◽  
Loss Prediction

This paper presents results of an experimental investigation into the effects of inlet skew on the flowfield of a large scale axial flow turbine cascade. The results are presented in terms of the development of the streamwise vorticity since, in classical terms, the streamwise vorticity generates the transverse velocity components that cause the generation of the secondary losses. Inlet skew is shown to have a profound effect on the distribution and magnitude of the generated losses. A number of correlations for the secondary losses are compared with the measured values and it is shown that the correlations are not adequate for accurate loss prediction purposes.

scholarly journals Recess Vane Passive Stall Control

1992 ◽  
Author(s):  
M. Ziabasharhagh ◽  
A. B. McKenzie ◽  
R. L. Elder
Keyword(s):  
Experimental Investigation ◽  
Axial Flow ◽  
Operating Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Inlet Distortion ◽  
Stall Margin Improvement ◽  
Stage Characteristic ◽  
Stall Control

An experimental investigation has been carried out on the influence of a vaned recessed casing treatment on the stall margin improvement of axial flow fans with different hub to tip ratio, with and without inlet distortion. The inlet distortion tests were conducted on a 0.5 hub to tip ratio fan and significant increases in the flow range with only small drops in operating efficiency were observed. The clean flow tests were conducted on higher hub to tip ratio fans (0.7 and 0.9). In each case the stage characteristic was compared with the results obtained with a solid casing. Significant increases in the flow range, with only modest or no loss in operating efficiency, were observed for optimum configurations at both diameter ratios.

Increasing Inducer Stability and Suction Performance With a Stability Control Device

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
R. Lundgreen ◽  
D. Maynes ◽  
S. Gorrell ◽  
K. Oliphant
Keyword(s):  
Fluid Dynamic ◽  
Leading Edge ◽  
High Energy ◽  
Stability Control ◽  
Control Device ◽  
Design Flow ◽  
Flow Coefficient ◽  
Blade Tip ◽  
Rotordynamic Forces ◽  
Suction Performance

An inducer is used as the first stage of high suction performance pump. It pressurizes the fluid to delay the onset of cavitation, which can adversely affect performance in a centrifugal pump. In this paper, the performance of a water pump inducer has been explored with and without the implementation of a stability control device (SCD). This device is an inlet cover bleed system that removes high-energy fluid near the blade leading edge and reinjects it back upstream. The research was conducted by running multiphase, time-accurate computational fluid dynamic (CFD) simulations at the design flow coefficient and at low, off-design flow coefficients. The suction performance and stability for the same inducer with and without the implementation of the SCD has been explored. An improvement in stability and suction performance was observed when the SCD was implemented. Without the SCD, the inducer developed backflow at the blade tip, which led to rotating cavitation and larger rotordynamic forces. With the SCD, no significant cavitation instabilities developed, and the rotordynamic forces remained small. The lack of cavitation instabilities also allowed the inducer to operate at lower inlet pressures, increasing the suction performance of the inducer.

Improved criteria for stall-free preliminary design of axial compressor of aero gas turbine engines

2018 ◽  
Vol 233 (9) ◽  
pp. 3286-3297 ◽  
Author(s):  
MR Aligoodarz ◽  
A Mehrpanahi ◽  
M Moshtaghzadeh ◽  
A Hashiehbaf
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Axial Compressor ◽  
Axial Flow ◽  
Design Criterion ◽  
Flow Coefficient ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Parameter Ranges ◽  
Axial Flow Compressors

A worldwide effort has been devoted to developing highly efficient and reliable gas turbine engines. There exist many prominent factors in the development of these engines. One of the most important features of the optimal design of axial flow compressors is satisfying the allowable range for various parameters such as flow coefficient, stage loading, the degree of reaction, De-Haller number, etc. But, there are some applicable cases that the mentioned criteria are exceeded. One of the most famous parameters is De-Haller number, which according to literature data should not be kept less than 0.72 in any stage of the axial compressor. A deep insight into the current small- or large-scale axial flow compressors shows that a discrepancy will occur among design criterion for De-Haller number and experimental measurements in which the De-Haller number is less than the design limit but no stall or surge is observed. In this paper, an improved formulation is derived based on one-dimensional modeling for predicting the stall-free design parameter ranges especially stage loading, flow coefficient, etc. for various combinations. It was found that the current criterion is much more accurate than the De-Haller criterion for design purposes.

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