On centrifugal pumps

In the present paper, epsilon (e) in the Omega vortex identification criterion (Ω method) is defined as an explicit function in order to apply the Ω method to different cases and even different time steps for the unsteady cases. In our method, e is defined as a function relating with the flow without any subjective adjustment on its coefficient. The newly proposed criteria for the determination of e is tested in several typical flow cases and is proved to be effective in the current work. The test cases given in the present paper include boundary layer transition, shock wave and boundary layer interaction, and channel flow with different Reynolds numbers.

Determination of epsilon for Omega vortex identification method

Effects of flow pattern on hydraulic performance and energy conversion characterisation in a centrifugal pump

Rotor-stator interaction in axial pumps can produce pressure fluctuations and further vibrations even damage to the pump system in some extreme case. In this paper, the influence of tip clearance on pressure fluctuations in an axial flow water pump has been investigated by numerical method. Three-dimensional unsteady flow in the axial flow water pump has been simulated with different tip clearances between the impeller blade tip and the casing wall. In addition to monitoring pressure fluctuations at some typical points, a new method based on pressure statistics was proposed to determine pressure fluctuations at all grid nodes inside the whole pump. The comparison shows that the existence of impeller tip clearance magnifies the pressure fluctuations in the impeller region, from the hub to shroud. However, the effect on pressure fluctuation in the diffuser region is not evident. Furthermore, the tip clearance vortex has also been examined under different tip clearances.

Influence of tip clearance on pressure fluctuations in an axial flow pump

In the present review, recent progress on the vortex identification methods are introduced with a focus on the newly proposed omega method (Ω method). The advantages of Ω method are summarized with many illustrating examples. Furthermore, comparing with other existing methods (e.g., Q criterion and λ2 criterion), one of the characteristics of Ω method is its independence on the chosen threshold values for vortex identifications. The important parameters involved for the practical applications of Ω method are further discussed in detail together with the physical interpretation of the Ω and some suggestions of the future work. Other emerging topics (e.g., Lagrangian coherent structure and Rortex) are also introduced with comments.

A selected review of vortex identification methods with applications

Cavitation is a challenging flow abnormality that leads to undesirable effects on the hydraulic behaviour of centrifugal pumps. This study analyses the cavitating flow at a normal flow rate using t...

Entropy generation analysis for the cavitating head-drop characteristic of a centrifugal pump:

Cavitation is a challenging flow abnormality that leads to undesirable effects on the energy performance of the centrifugal pump and the reliable operation of the pump system. The onset and mechanism of a phenomenon that results in unsteady cavitation must be realised to ensure a reliable operation of pumps under the cavitation state. This study focuses on cavitation instability at normal flow rate, at which point the unsteady cavitation occurs as the available net positive suction head (NPSHa) falls below 5.61 m for the researched pump. An ameliorative algorithm–united algorithm for cavitation vibration analysis is proposed on the basis of short time Fourier transform (STFT) and Wigner–Ville distribution (WVD). The STFT–WVD method is then tested using vibration data measured from the centrifugal pump. The relationship between vibration and suction performance indicates that the inception and development of cavitation can be effectively detected by the distribution and intensity of the united algorithm at the testing points. Intermediate frequency components at approximately 6 kHz fluctuate initially with the development of cavitation. A time–frequency characteristic is found to be conducive to monitoring the cavitation performance of centrifugal pumps.

An experimental study on the cavitation vibration characteristics of a centrifugal pump at normal flow rate

This paper presents an investigation of pressure fluctuation of a single-suction volute-type centrifugal pump, particularly volute casing, by using numerical and experimental methods. A new type of...

https://journals.sagepub.com/doi/pdf/10.1155/2014/972081

Numerical Investigation of Pressure Fluctuation in Centrifugal Pump Volute Based on SAS Model and Experimental Validation

Flow-Induced Noises in a Centrifugal Pump: A Review

Most of the pumps working under two phase flows conditions are used in petroleum industry applications, like electrical submersible pumps (ESP) for hydrocarbon fluids, in chemistry, nuclear industries and in agriculture for irrigation purposes as well. Two-phase flows always deteriorate overall pump performances compared with single flow conditions. Several papers have been published aiming to understand flow physics and to model all the main mechanisms that govern gas pocket formation and surging phenomena. These mechanisms depend on the pump type, the impeller geometry, the rotational speed, design and off-design liquid flow rate conditions, the volumetric gas fraction, the fluid properties and the inlet pressure. In the present paper, a review on two phase performances from various centrifugal pumps designs is presented, mainly based on experimental results. The main focus is devoted to detect the significant geometrical parameters that: (1) Modify the pump head degradation level under bubbly flow regime assumption; (2) Allow single stage centrifugal pumps keep working under two-phase flow conditions with high inlet void fraction values before pump shut down, whatever the pump performance degradations and liquid production rates should be. Because most of the published experimental studies are performed on dedicated laboratory centrifugal pump models, most of the present review is based on air-water mixtures as the working fluid with inlet pressures close to atmospheric conditions. The following review supposes that gas phase is considered as a non-condensable perfect gas, while the liquid phase is incompressible. Both phases are isolated from external conditions: neither mass nor heat transfer take place between the phases.

https://www.mdpi.com/1996-1073/12/6/1078/pdf

Qiaorui Si

Papers

Entropy generation analysis for the cavitating head-drop characteristic of a centrifugal pump:

An experimental study on the cavitation vibration characteristics of a centrifugal pump at normal flow rate

Numerical Investigation of Pressure Fluctuation in Centrifugal Pump Volute Based on SAS Model and Experimental Validation

Flow-Induced Noises in a Centrifugal Pump: A Review

A Review of Design Considerations of Centrifugal Pump Capability for Handling Inlet Gas-Liquid Two-Phase Flows