Flow Passage Of Pump Research Articles

Influence of blade tip cutting on the flow loss characteristics of side channel pump

A comprehensive analysis of flow loss mechanisms in a side channel pump is put forth in this research. First, the correlation between the cutting angle and loss characteristics in each flow passage of the side channel pump is investigated. Second, the exact regions of the internal loss distributions in the flow passages of the pump are analyzed. Finally, the relationship between the dissipation effect and enstrophy is ascertained among the cutting angles. Generally, the flow loss steadily rises with the increase in cutting angle from 10° to 20° in the impeller. However, at 30°, the losses experience a substantial decrease and then increase thereafter. Meanwhile, the loss gradient in the side channel rises linearly with the increase in cutting angle from 10° to 40°. Cutting angles of 20°, 30°, and 40° revealed the minimum value of energy loss at the outer radius of the impeller compared to the original model. In the side channel passage, all cutting angles revealed a fairly lower magnitude of flow losses than in the original model. Noticeably, the dissipation effect and enstrophy share common resemblances, with a concentration of high enstrophy regions observed in plane 1. The impeller passage portrayed a higher dominancy of the enstrophy region, which nevertheless weakens to a minimum in the side channel for all the cutting angles. The findings of this study provide valuable insights into optimizing the design and performance of side channel pumps.

Role of wall roughness on interaction of leakage flow and main flow in a mixed flow pump with tip clearance

Due to machining precision, spraying coating, cavitation, and erosion, walls of pump flow passage components have different roughness, which will affect the flow state near the wall and even the main flow. In the present work, four types of roughness Ra = 0, 0.1, 1, and 10 μm are set to investigate the influence of wall roughness on the interaction of leakage flow and main flow in a mixed flow pump with tip clearance. Results show that the interaction area of leakage flow and main flow can be divided into three regions: (a) tip clearance zone, (b) shear flow zone, and (c) primary vortex zone. In the tip clearance zone, as roughness increases, the velocity magnitude and its derivative at the same wall distance gradually decrease, and the velocity angle at blade tip continuously increases in the inner circular boundary layer. As the roughness increases, the leakage flow gradually decreases, especially in the center chord region. In the shear flow zone, the velocity gradient rapidly decreases along the direction of pressure side to suction side, and finally, it becomes stable. As roughness increases, the velocity gradient intensity decreases, and the main reason is that the differences of velocity magnitude and velocity direction between the inner circular boundary layer and potential region decrease. In the primary vortex zone, the tip leakage vortex core indicated by the Liutex vortex method coincides with the low-pressure core location. As the roughness increases, the tip leakage vortex core becomes closer to the next blade. The pressure coefficient and vorticity of the tip leakage vortex core decrease with increasing of roughness, and the slopes remain constant on different cross sections with value of 5.9 × 103 and 2.4 × 103 m−1, respectively.

Internal Cavitating Flow Distribution and Performance Comparison of a Disc Pump with Radial Straight Blade

Disc pumps with radial straight blade are unconventional designs that have been developed for hard-to-pump mixtures for many industrial applications. They are frequently used in chemical industries, sub-sea petroleum pumping systems with multi-phase media and so on. Due to the radial straight blade arrangement, they may suffer from cavitation onsets when being used under different pressure conditions. To study the influence of cavitation characteristic inside the present disc pump flow passages, experimental data analysis on a radial blade disc pump for a wide flow rate range (0 to 110 m3/h) is obtained. In addition, the Reynolds averaged (RANS) approach using the RNG k-ε turbulence model, is carried out under different working conditions with and without cavitation modelling. Two different pump meshing models are also implemented: the first one without hub and shroud side channels between the discs and the volute casing, the second one with both side channels corresponding to the complete real case geometry. The comparisons between experimental and numerical results reveal first that the complete geometry meshing must be used to recover the experimental performance curve especially at low flow rates whatever the rotational speed. Secondly, the cavitation effect is found to take place in precise locations (straight blade and connection column) inside the impeller at high rotational speed and high flow rates. Their effects correspond to the unexpected performance curve deterioration found for the highest rotational speed and high flow rates. Moreover, with the decrease of the inlet absolute pressure, the cavitation degree becomes serious, and the coupling phenomenon of straight blade cavitation and connection column cavitation is formed, which enlarges the scope and enhances the degree of cavitation. The present study proposes a data reduction procedure when open loop experimental testing procedure is used for specific disc pump design and the importance of the impeller-side channels interactions on head pump decrease at low flow coefficients.

The finite element modeling of the impacting process of hard particles on pump components

Abstract Shield pumps which transport a variety of complex media are widely used in chemical industry, mineral industry, and other fields. However, the hard particles in the media erode the flow passage in the shield pump, seriously affecting the service life of the pump. Therefore, it is important to study the erosion process in the flow passage to extend the service life of the pump. This erosion process in the shield pump can be investigated by experiments, but it is difficult for the current experimental method to copy the real industrial service environment of impellers. For example, the environment temperature and speed range are found difficult to be reached by the current experimental method. Comparatively, the simulation by finite element method can overcome the above deficiency. In this article, the ANASYS software is used to simulate the erosion process in shield pump flow passage due to hard particles. Specifically, the structural static analysis module is used to build the model of thermal barrier coating components and hard particle components. Then the variation law of stress, strain, and material deformation of the flow passage components under concentrated force is obtained. Second, the extended finite element method is used to study the crack propagation caused by the erosion process. A linear elastic–linear softening constitutive model is established to simulate the stress variation during the crack propagation and material removal under the continuous erosion from hard particles. The proposed law regarding stress variation and crack propagation in the erosion process in this study contributes to theoretical support for damage detection and service life extension of shield pumps.

Pressure fluctuation characteristics of centrifugal pump at low flow rate

The current investigation is aimed to simulate the unsteady internal flows in a centrifugal pump impeller with seven twisted blades by using a three-dimensional Navier-Stokes equations with Scale-adaptive simulation (SAS) turbulence model. A detailed analysis of the results at design flow rate Q0 and low flow rate 0.5Q0 and 0.3Q0, is presented. Unsteady flow analyses in centrifugal pump are focused mainly on the volute. The calculation results of pump head and efficiency at different flow rate conditions is in good agreement with the experimental data. Nine monitor points are positioned in the volute. The frequency of pressure fluctuations on all monitor points are analyzed and discussed. Under different flow rate conditions, the dominant frequency of pressure fluctuation in volute are the blade pass frequency and its integer multiples, the blade pass frequency always played the dominant role, and the largest pressure fluctuation maximum amplitude occurs near the volute tongue zone. With the flow rate decrease, the intensity of pressure fluctuation gets stronger, especially in spiral zone is the most obvious and the amplitude value of pressure fluctuation is the most dramatically increased. The maximum amplitude of pressure fluctuation in spiral zone is about 2∼3 times of design flow rate. Moreover, the streamline distribution in pump flow passage at flow rate Q0, 0.5Q0 and 0.3Q0 is analyzed. The results demonstrate that with the flow rate decrease, the vortex in the impeller flow passage is generating, developing and even blocking the whole impeller flow passage, which is disturbs the internal flow field and induces the strong pressure fluctuations in volute spiral zone. This research provided a reference for expanding the operation range of centrifugal pump and optimization design of volute in centrifugal pump.

The Effect of Pump Intake Leaning Angle and Flow Rate on the Internal Flow of Pump Sump

Pump sump system or pumping stations are built to draw water from a source such as river and used for irrigation, thermal power plants etc. If pump sump is improperly shaped or sized, air entraining vortices or submerged vortices may develop. This may greatly affect pump operation if vortices grow to an appreciable extent. Moreover, the noise and vibration of the pump can be increased by the remaining of vortices in the pump flow passage. Therefore, the vortices in the pump flow passage have to be reduced for a good performance of pump sump station. In this study, the effect of pump intake leaning angle and flow rate on the pump sump internal flow has been investigated. There are three cases with different leaning angle. Moreover, a pipe type with elbow also has been studied. The flow rate with three classes of air entraining vortices has been examined and investigated by decreasing the water level. The result shows that the air entraining vortices easily occurs at the pump intake with large leaning angle. Moreover, the elbow type of the pump intake easily occurs air entraining vortices at the high flow rate (or velocity) in comparison to other pump intake type.

Effect of suction pipe leaning angle and water level on the internal flow of pump sump

The pump sump, which connects forebay and intake of pump station, supplies good flow condition for the intake of the pump. If suction sumps are improperly shaped or sized, air entraining vortices or submerged vortices may develop. This may greatly affect pump operation if vortices grow to an appreciable extent. Moreover, the noise and vibration of the pump can be increased by the remaining of vortices in the pump flow passage. Therefore, the vortices in the pump flow passage have to be reduced for a good performance of pump sump station. In this study, the effect of suction pipe leaning angle on the pump sump internal flow with different water level has been investigated by CFD analysis. Moreover, an elbow type pipe was also investigated. There are 3 leaning angles with 0°, 45° and 90° for the suction pipe. The suction pipe inlet centre is kept same for all the cases. In addition, the three different water levels of H/D=1.85, 1.54, and 1.31, is applied to different suction pipe types. The result shows that the amount of air sucked into the suction pipe increases with increasing the suction pipe leaning angle. Especially for the horizontal suction pipe, there is maximum air sucked into the suction pipe. However, there is certain effect of the elbow type bell mouth installation in the horizontal suction pipe on suppressing the amount of air sucked into the pipe. Moreover, vertical suction pipe plays an effective role on reducing the free surface vortex intake area.

The effect of suction pipe leaning angle on the internal flow of pump sump

A better flow condition for the intake of pump is provided by the sump pump that connects the forebay to the intake of the pump station. If the suction sump is improperly shaped or sized, air-entraining vortices or submerged vortices may develop. These phenomena may greatly affect pump operation if vortices become sufficiently large. Moreover, any remaining vortices in the pump flow passage may result in an increase in the noise and vibration of the pump. Therefore, the vortices in the pump flow passage must be reduced to achieve good pump sump station performance. In this study, the effect of suction pipe leaning angle on the pump sump’s internal flow is investigated. Additionally, a pipe type with an elbow shape is investigated. The results show that the air entraining vortices occur under the condition of a water level ratio H/D = 1.31 for each suction pipe type.

Numerical simulation and analysis of cavitation flows in a double suction centrifugal pump

Cavitation is an unsteady phenomenon, which is nearly inevitable in pumps. It would degrade the pump performance, generate vibrations and noises, and even erode pump flow passage components. The double suction centrifugal pump at design flow rate and large flow rate is numerically simulated using the k-ω turbulence model and the mass transport cavitation model. As a result, the calculated variation of pump head with pump inlet pressure agreed well with the experimental data. The results demonstrate that the numerical model and method can accurately predict the cavitation flows in a double suction centrifugal pump. The cavitation characteristics are analysed in great details. In addition, based on the calculation results, the reason that the plunge of pump head curve is revealed. It is found that the steep fall of pump head happens when the cavity reaches the blade to blade throat and the micro-vortex group appears at the back of the blade suction side. At the same time, this practice can provide guidance for the optimal design of double suction pumps.

Effects of blade rotation angle deviations on mixed-flow pump hydraulic performance

By model test and numerical simulation, this paper analyzed the effects of different blades with varying rotation angle deviations on the hydraulic performance of a mixed-flow pump. It was found that when some blades had rotation angle deviations, the hydraulic performance curves of the mixed-flow pump would move. With a positive deviation, the curves moved towards the large flow rate; with a negative deviation, the curves moved towards the small flow rate. When some blades had rotation angle deviations, the symmetry and uniformity of the pressure distribution inside the mixed-flow pump flow passage both decreased; the larger the deviation, the greater the decrease. When a single blade had a large rotation angle deviation, a rather clear low pressure area was formed, lowering the cavitation performance. When two adjacent blades changed simultaneously, under the small flow rate condition, adverse pressure gradient and flow separation occurred in the flow field, and a hump appeared in the head curve and the operation stability of the mixed-flow pump dropped significantly. Near the best efficiency point (BEP), the simultaneous change of two alternate blades produced a more significant change of pressure in the flow passage, with an even larger area. Compared to the effect of two adjacent blades, two alternate blades, when changed simultaneously, made the mixed-flow pump slightly less efficient, but with a flatter efficiency curve and relatively wider high efficiency area. By fitting the test results, a functional relation among the BEP of the mixed-flow pump Q BEP, the number of deviated blades N, and blade rotation angle deviation α was established, thus realizing an effective prediction of the BEP of the mixed-flow pump when blade rotation angles have deviations.

Fluid dynamics aspects of miniaturized axial-flow blood pump

Rotary blood pump (RBP) is a kind of crucial ventricular assist device (VAD) and its advantages have been evidenced and acknowledged in recent years. Among the factors that influence the operation performance and the durability of various rotary blood pumps, medium property and the flow features in pump's flow passages are conceivably significant. The major concern in this paper is the fluid dynamics aspects of such a kind of miniaturized pump. More specifically, the structural features of axial-flow blood pump and corresponding flow features are analyzed in detail. The narrow flow passage between blade tips and pump casing and the rotor-stator interaction (RSI) zone may exert a negative effect on the shear stress distribution in the blood flow. Numerical techniques are briefly introduced in view of their contribution to facilitating the optimal design of blood pump and the visualization of shear stress distribution and multiphase flow analysis. Additionally, with the development of flow measurement techniques, the high-resolution, effective and non-intrusive flow measurement techniques catering to the measurement of the flows inside rotary blood pumps are highly anticipated.

Design optimization of flow channel and performance analysis for a new-type centrifugal blood pump

In this paper, a new-type centrifugal blood pump, whose impeller is suspended inside a pump chamber with hydraulic bearings, is presented. In order to improve the hydraulic performance of the pump, an internal flow simulation is conducted to compare the effects of different geometrical parameters of pump flow passage. Based on the numerical results, the pumps can satisfy the operation parameters and be free of hemolysis. It is noted that for the pump with a column-type supporter at its inlet, the pump head and hydraulic efficiency decreases compared to the pump with a step-type support structure. The performance drop is caused by the disturbed flow upstream impeller inlet. Further, the unfavorable flow features such as reverse flow and low velocity in the pump may increases the possibility of thrombus. It is also confirmed that the casing shape can little influence pump performance. Those results are helpful for design optimization in blood pump development.

Dynamics of cavity development in the centrifugal pump impeller

In this paper, some features of cavity development are presented for a case of a flow around the blade profile of the centrifugal pump impeller. Based on the photographs obtained in visualization of the cavitation centrifugal pump operation conditions, we refined the shape, volumes, and parameters of cavity growth in the centrifugal pump flow passage. Also presented are the relations characterizing the features of cavity formation in the centrifugal force field.

A miniature pump with a fluid dynamic bearing

This paper describes the development of a miniature pump having an impeller with an exit diameter of 24 mm supported with the motor rotor by a fluid dynamic bearing. Tests verify that the miniature pump is stable and quiet for rotational speeds larger than 4000 min-1. The three-dimensional turbulent flow in the entire pump flow passage and the laminar flow in the fluid dynamic bearing were then simulated numerically. The average pump performance was well predicted by the simulations. Both the tests and the simulations show that there is no obvious Reynolds effect for the miniature pump within the tested range of rotational speeds. The numerical results also show that the bearing capacity of the fluid dynamic bearing increases with the pump rotor rotational speed and the eccentricity ratio of the journal to the bushing. This pump is very compact, so it is a promising device for surgical use.

Demonstration and Validation of a 3D CFD Simulation Tool Predicting Pump Performance and Cavitation for Industrial Applications

Due to complexities in geometry and physics, computational fluid dynamics (CFD) pump simulation has historically been very challenging and time consuming, especially for cases with cavitation. However, with the evolution and innovation of CFD technologies, pump cavitation simulation has improved significantly in recent years. In view of these developments, this paper will discuss a new generation CFD tool for pump cavitation simulation, using an axial flow water pump as a demonstration case. A novel CFD methodology and advanced cavitation model will be presented and discussed. Key components that are relevant to the improvement of accuracy and CFD simulation speed will be discussed in detail. An axial flow water pump is chosen as the test case to demonstrate and validate the capability and accuracy of the code discussed. Simulation results include pump head, hydraulic efficiency, and cavitation characteristic in terms of incipient net positive suction head for the whole pump flow passages using both multiple reference frame and transient approaches. Multiple operation conditions, from 70% to 120% of duty flow rate, have been evaluated and will be projected against experimental data. Furthermore, simulated cavitation patterns will be compared with video images recorded during the experiments.

Structural features and behavior of seals in the hydrogen pump flow passages

Some features of designing seals for hydrogen pumps used in turbopump assemblies of liquid-propellant rocket engines are considered. These features are interrelated with specific physical and chemical characteristics of the working medium, namely, hydrogen.