Some Unsteady Fluid Forces on Pump Impellers

Miskovish, R. Scott; Brennen, Christopher E.

doi:10.1115/1.2910078

Cited by 9 publications

(4 citation statements)

References 4 publications

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“…This phenomenon occurs when the rotation axis of the rotor-shaft system is slightly displaced from its mid-position by effects of the fluid. The rotodynamic forces will be a function of the frequency of the rotor, but not of the displacement [26]. It is common that this phenomenon appears at subsynchronous frequency [24].…”

Section: Fluid-induced Rotordynamic Forcesmentioning

confidence: 99%

Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

Bolaños

Botero

2021

IyU

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Objective: Identify and characterize subsynchronous hydrodynamics phenomena in a low specific speed centrifugal pump based on its four-quadrant characteristic curve. Materials: A 1.5 HP ITT Goulds pump instrumented with pressure transductors, an accelerometer, a torque sensor and a tachometer. Flow rate measurement was done with an ultrasonic transit time clamp-on flow meter. Methods: Time and frequency domain analysis with phase analysis were used to identify spectral components linked to hydrodynamic phenomena such as rotating stall and surge. Results and discussion: This work approaches an alternative method to calculate the phase angle using pressure signals without filtering. Related with hydrodynamic phenomena, the evidence collected suggests the presence of rotating stall in some operation points of the four-quadrant characteristic curve. Furthermore, in the third quadrant, rotating stall coexist with surge. Conclusions: The instrumentation and methods regarded in this work allow to collect evidence to identify in-phase and out of phase subsynchronous hydrodynamic phenomena. The classic cross-correlation-based method was improved to ease the diagnosis of subsynchronous phenomena by visual inspection. A new quantitative approach was introduced to detect subsynchronous phenomena, based on the Fourier analysis; it was validated with a case study for which the classical method was not suitable.

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Section: Fluid-induced Rotordynamic Forcesmentioning

confidence: 99%

Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

Bolaños

Botero

2021

IyU

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“…In this paper we will focus on the forces, but it is clear that a parallel construct is relevant to a set of rotordynamic bending moments that also determine the lines of action of the forces. For these details the reader is referred to Reference [6].…”

Section: Notationmentioning

confidence: 99%

“…Though some early data on the rotordynamic forces in a centrifugal pump were obtained by Shoji and Ohashi [8], the Caltech program added greatly to the data base. Data were obtained for many different types of impellers (centrifugal and axial, shrouded and unshrouded, with and without cavitation), for many different types of volutes and for parametric variations of the forces with pump operating point, pump cavitation and various clearances and other factors [6,7,[9][10][11][12][13][14][15][16][17][18][19]. Typical data for the dimensionless normal and tangential forces, F n and F t ; as a function of the frequency ratio, o=O; are presented in Figure 3 for a conventional centrifugal pump impeller operating in a single vaneless volute.…”

Section: Measurements In Centrifugal Pumpsmentioning

confidence: 99%

Fluid-induced rotordynamic forces and instabilities

Brennen

Acosta

2006

Struct. Control Health Monit.

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SUMMARYIn the late 1970s, the authors began a collaboration with our colleague Tom Caughey that helped define a new set of fluid-structure interaction phenomena in turbomachines, namely fluid-induced rotordynamic forces and instabilities. That collaboration and the 31 joint "ABC" papers it produced epitomized Tom Caughey's genius and we reprise it here in his honor.The design of the Space Shuttle Main Engine (SSME) pushed beyond the boundaries of many known technologies. In particular, the rotating speeds and operating conditions of the high speed liquid oxygen and liquid hydrogen turbopumps were extreme and early testing revealed a whirl instability whose magnitude exceeded expectations and allowable limits. It was suspected and later proven that fluid-induced rotordynamic effects were a contributing factor and yet very little was known of such phenomena. As one of the efforts seeking understanding, we constructed a facility to measure fluid-induced rotordynamic forces. This was subsequently used in a broad range of investigations. Initially, the effort was directed to understanding the source and parametric variations of destabilizing fluid forces. Later various components of the flow in a high speed turbopump were investigated. And finally, some ameliorative measures and their effectiveness were examined. This paper reviews this body of knowledge and the lessons learnt along the way.

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“…RSI is generated because pump-turbines consist of a bladed rotor (bladed impellerrunner) and a vaned stator (guide vanes or wicket gates in diffuser-distributor). When the pump-turbine is under operation, there is a fluid-dynamic load every time a blade passes in front of a guide vane, producing a periodic load at blade passing frequency and its harmonics [1][2][3][4][5][6][7]. Forces due to RSI are applied to the impeller-runner which is designed to be as small as possible in order to minimize manufacture and transport expenses leading to a reduced thickness/weight ratio and a high power/weight ratio.…”

Section: Introductionmentioning

confidence: 99%

Monitoring of Rotor-Stator Interaction in Pump-Turbine Using Vibrations Measured with On-Board Sensors Rotating with Shaft

Rodríguez

Mateos-Prieto

Egusquiza

2014

Shock and Vibration

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Current trends in design of pump-turbines have led into higher rotor-stator interaction (RSI) loads over impeller-runner. These dynamic loads are of special interest having produced catastrophic failures in pump-turbines. Determining RSI characteristics facilitates the proposal of actions that will prevent these failures. Pressure measurements all around the perimeter of the impellerrunner are appropriate to monitor and detect RSI characteristics. Unfortunately most installed pump-turbines are not manufactured with in-built pressure sensors in appropriate positions to monitor RSI. For this reason, vibration measurements are the preferred method to monitor RSI in industry. Usually vibrations are measured in two perpendicular radial directions in bearings where valuable information could be lost due to bearing response. In this work, in order to avoid the effect of bearing response on measurement, two vibration sensors are installed rotating with the shaft. The RSI characteristics obtained with pressure measurements were compared to those determined using vibration measurements. The RSI characteristics obtained with pressure measurements were also determined using vibrations measured rotating with shaft. These RSI characteristics were not possible to be determined using the vibrations measured in guide bearing. Finally, it is recommended to measure vibrations rotating with shaft to detect RSI characteristics in installed pump-turbines as a more practical and reliable method to monitor RSI characteristics.

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Some Unsteady Fluid Forces on Pump Impellers

Cited by 9 publications

References 4 publications

Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

Four-quadrant Characterization of Hydrodynamic Phenomena in a Low Specific Speed Centrifugal Pump

Fluid-induced rotordynamic forces and instabilities

Monitoring of Rotor-Stator Interaction in Pump-Turbine Using Vibrations Measured with On-Board Sensors Rotating with Shaft

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