Performance Of Jet Pump Research Articles

CFD-Based Study of Nozzle Section Geometry Effects on the Performance of an Annular Multi-Nozzle Jet Pump

CFD simulation and analysis of the internal flow field of the annular multi-nozzle jet pump are carried out to study the effects of nozzle section geometries on performance of the pump based on the finite volume method and realizable k-ε model. The results show that the square nozzle peak efficiency is 3% higher than that of the circular nozzle and 4.1% higher than that of the triangular nozzle. According to the simulation results, the mixing mechanism of the working fluid and second fluid is analyzed on the basis of the vortex dynamics. The results show the following: the recirculation area and the friction loss of the non-circular nozzle are reduced, and the mixing effect is improved; the streamwise vortex plays a major role in the mixing process and decays to an extremely small value at the end of the throat after attenuating rapidly in the suction chamber; compared with the streamwise vortex, the strength of the spanwise vortex is relatively stronger; the spanwise vortex still fluctuates after developing to a certain extent in the throat; the maximum streamwise vorticity peak value of the square nozzle is 31% more than that of the circular nozzle and 39% more than that of the triangular nozzle; the maximum spanwise vorticity peak value of the square nozzle is 19% less than that of the circular nozzle and 12% less than that of the triangular nozzle.

Numerical investigation of the cavitation performance of annular jet pumps with different profiles of suction chamber and throat inlet

To find the influence of the suction chamber and throat inlet profiles on the cavitation performance of an annular jet pump (AJP), a numerical method using a combination of the realizable k–ϵ turbulence model and the Schnerr–Sauer cavitation model was applied. This paper comprehensively studied the cavitation performance of AJPs with a polygonal line profile (POL) and a streamlined profile (STR). The results showed that the pump efficiency (η) can be increasedby using the STR and the largest increase was 1.4%. Since the throat is smoothly connected with the suction chamber in the AJP with STR, flow separation and local low pressure did not appear. The critical flow rate ratio (qc ) of the AJP with STR was higher than that of the AJP with POL, implying that the former had a wider normal working range. During critical working, the cavitation region in the AJP with STR was narrower than that of the AJP with POL. Importantly, the region of cavitation inception and development in the AJP with STR was closer to the downstream. Hence, it was concluded that the cavitation in the AJP with STR had less influence on the inner flow field.

Influence of suction chamber profile on flow field of annular jet pump

Jet pump is a kind of fluid machinery, which uses jet shear and turbulent diffusion to transfer mass and energy. It is widely used in water project, civil engineering and other fields. In order to investigate the influence of suction chamber profile on flow field of annular jet pump, the conical suction chamber and the streamlined suction chamber were compared by applying turbulence numerical simulation method. The performance, pressure characteristics, velocity and turbulent energy distributions of annular jet pumps with two suction chambers are analysed. The calculation shows that compared with the traditional conical suction chamber, the efficiency of annular jet pump with streamlined suction chamber is improved at low flow ratio, and the change is not obvious at high flow ratio. In the same section, the cross sectional area of streamlined suction chamber is slightly larger than that of conical suction chamber, so the primary flow velocity near the wall is slightly lower, which can reduce the friction loss caused by high speed wall-attached flow. In addition, the smooth turning of the primary flow in streamlined suction chamber can weaken the extrusion on the entrained flow field. Different from the conical suction chamber, the streamlined suction chamber is smoothly connected with throat without sudden corner change, which can eliminate the low pressure near the inlet wall of throat, improve the wall pressure distribution and reduce the possible cavitation. The research results of suction chamber profile of annular jet pump can provide scientific basis for the popularization and application of jet pump.

A Novel Approach for Identifying Gas Cavitation in Oil Jet Pump for Lubrication System

Gas cavitation has significant influence on oil jet pump in lubrication system of turbo machinery. This study provides a novel approach for identifying gas cavitation in oil jet pump. Such an approach accounts for the physical process of gas cavitation and its effect on the performance of oil jet pump. The performance of oil jet pump under variable working conditions is systematically measured and quantified from experiment and numerical simulation results. Based on the frequency characteristics of cavitation process and its action mechanism, a novel approach for the identification of gas cavitation is provided. Results shown that gas cavitation emerges at =1.68 and fades away at =1.31 with dissolve air content =110ppm in lubrication oil. Here, the dissolved air content in lubrication oil is 6.3 times larger than that in water, and the oil jet pump is more prone to suffer from cavitation than water jet pump by 16%. This study promotes a deeper understanding on the mechanics of gas cavitation affects fluid machinery in lubrication system.

Effects of Liquid Density on Jet Pump Performance

This research covers the experimental results obtained in the current work. A set of experiments were carried out to study the effect of some parameters on the performance of jet pump. The subject is treated experimentally on a special test rig, with the primary jet water and the secondary different density of salt water. Suction characteristics of a jet pump in different density of salt water and different pressure and different suction pipe sizes were analyzed. Conclusions were drawn by the performance test as follow: size of suction pipe diameter has major influence on the inlet volume of salt water, specific gravity size of salt water has major influence on the trends of the inlet volume of salt water. The conclusion of correlation between the different specific gravity and the inlet volumes of salt water was concluded by curves in this paper.

Study on energy conservation water injection system of offshore platform based on jet pump

In order to reduce energy consumption of water injection development of offshore platform, one idea of jet pumps with characteristics of suction replace the gate valve of water injection wells was introduced. Taking 14 injection wells at a platform in Bohai as the study object, three types of jet pumps which are called JP1, JP2 and JP3 were designed. The corresponding three-dimensional models were established and the Realizable k-ε model of ANSYS was applied to study the influence of jet pump nozzle-throat clearance on water injection rate. Moreover, the injection performance of structure-optimized jet pumps was tested. Three conclusions could be drawn. First, JP1, JP2 and JP3 express the best water injection performance with the optimal nozzle-to-throat clearance which is 4 mm, 5 mm and 6 mm. Second, the water injection rate could satisfy the demand of water injection platform and simulation results are similar to the experimental ones when the water injection rate range of three kinds of jet pump is 183–272 m3/d, 263–393 m3/d and 634–1149 m3/d respectively. Third, compared with the throttle valve water injection system at offshore platform, the jet pump water injection system could save about 1,150,000 kW h per year.

Performance comparison of jet pumps with round and sharp edge of small opening in oscillatory flow

Owing to the capability to induce a time-averaged pressure drop in oscillatory flow, a jet pump has been used to suppress the Gedeon streaming in a looped thermoacoustic engine. The suppression capacity originates from the asymmetric pressure drop through the jet pump, and could be enhanced by rounding the edge of the jet pump in traditional view. This paper systematically probes the rounding effect on a jet pump and compares the performance of jet pumps with round and with sharp edge on small opening. The performance dependences on the taper angle and the cross-sectional area ratios, including the big-to-small opening area ratio of the jet pump and the small opening-to-pipe cross sectional area ratio, are analyzed and compared for the two types of jet pump. The results reveal a reversed and higher time-averaged pressure drop in the shape edge jet pump in contrast to that in the rounded jet pump. However, the round edge of the small opening can improve working efficiency of a jet pump.

Research on Urea Jet Pump Performance Characteristics using the Optimized NOx Removal Equipment in Diesel Engine

ABSTRACT There are many factors that affect the efficiency of NOx conversion in the diesel engine SCR (selective catalytic reduction) post-processing system. In this study, we researched the factors affecting the efficiency of NOx conversion by engine bench testing. The SCR system was applied to the Weichai WD615 engine exhaust. First, the system used DOC (Diesel Oxidation Catalyst)/DPF (Diesel Particulate Filter) of which DOC is a noble metal-containing filter, it lets the filter passes through converting nitrogen monoxide (NO) to nitrogen dioxide (NO2) for passive regenerations and to provide high hydrocarbon (HC) oxidation activity for active DPF regenerations, the DPF is a wall-flow filter used to trap the remaining soot that the DOC can not oxidize. The combined catalytic oxidation device improved the original SCR deNOx system, which we developed. The new catalytic oxidation apparatus has a simple structure and fundamentally solves the clogging problem of the SCR method and the defects led by the unstable gaseous ammonia generation. Secondly, we studied the influence of an increased urea injection on the conversion efficiency of NOx and the secondary pollution of NH3 at different speeds and torques of the engine. It was found that at the maximum removal rate, the downstream NOx concentration was only 1 ppm. The NOx conversion efficiency can reach 79.10% or more—even 99.90%. Finally, we used the KDS and the BOSCH urea injection pumps to analyze the effect of different pumps on the conversion efficiency of NOx. Hence, the matching diesel engine urea SCR post-processing system can reduce the emission concentration and pollution. There was little difference between the two pumps under most of the working conditions, although KDS was a little better than BOSCH under some individual conditions.

Impact of cross-sectional area ratio on time-averaged pressure drop induced by jet pump for thermoacoustic engine

Gedeon streaming, a time-averaged mass flow circulating throughout the loop configuration in the oscillating flow, can considerably deteriorate the thermal efficiency of traveling-wave thermoacoustic engine. Jet pump is characterized by a tapered channel with different inlet and outlet areas. It can produce a time-averaged pressure drop to suppress Gedeon streaming. In this study, the suppression mechanism of the jet pump in oscillatory flow is investigated, and the emphasis is put on the effect of cross-sectional area ratio on the performance of jet pumps with different taper angles. An experimental apparatus has been built to measure the time-averaged pressure induced by the jet pump. When the taper angle ranges from 3° to 9°, the time-averaged pressure drop and working efficiency can be improved by increasing cross-sectional area ratio, and the change of taper angle has little effect on the performance of jet pumps. However, as the taper angle increases beyond 9°, the performance of jet pump with a large cross-sectional area ratio degrades considerably. In addition, the time-averaged pressure drops induced by the jet pumps with different cross-sectional area ratios are similar, and the taper angle becomes more dominant for jet pump’s performance.

Simulative Study and Investigation of Cavity Formation and Its Effect on the Performance of Water Jet Pump

Simulative Study and Investigation of Cavity Formation and Its Effect on the Performance of Water Jet Pump

Effect of taper angle on the performance of jet pumps for a loop-structured thermoacoustic engine

Gedeon streaming, which circulates throughout the loop configuration with a time-averaged manner in the oscillating flow, can considerably deteriorate the efficiency of traveling-wave thermoacoustic engine. A jet pump is characterized by a tapered channel with different opening areas, which can produce a time-averaged pressure drop to suppress Gedeon streaming. Three jet pumps with different taper angles, i.e., 5°, 9°, 15°, are studied. Following Iguchi's hypothesis, the turbulent oscillating flow can be considered as a steady flow. The flow structures though the jet pumps are numerically simulated. Meanwhile, an experimental apparatus has been built to measure the performance of jet pump operating in the turbulent oscillating flow. The results show that the simulation is in a good agreement with the experiment data for the jet pumps with small taper angles. For the jet pump with 15° taper angle, the simulation results match well with the experiment data when the velocity at small opening of jet pump is higher than 50 m/s. However, when the velocity is lower, the simulation results deviate from the experiment data considerably, which can be attributed to the flow separation in the diverging direction operated differently in the steady flow and oscillating flow at lower velocity.

Study the Performance of water Jet Pump by Changing the Angle of Mixing Nozzle.

Study the Performance of water Jet Pump by Changing the Angle of Mixing Nozzle.

COMPUTATIONAL AND EXPERIMENTAL STUDY ON THE WATER-JET PUMP PERFORMANCE UNDER DIFFERENT GEOMETRICAL AND OPERATIONAL PARAMETERS

The aim of the present study is to investigate the performance of jet pump. The effect of geometrical and operational parameters on the jet pumps efficiency were determined numerically and experimentally. Numerical investigation was held firstly to determine the effect of diffuser angle, mixing chamber length, pump area ratio and driving nozzle position on the jet pump efficiency. Commercial computational fluid dynamics (CFD) solver ANSYS R 15.0-FLUENT using SST-turbulence model was used. The numerical results showed that jet pump efficiency increases with decreasing both of diffuser angle and mixing chamber length up to a certain value and then pump efficiency decreases. Also, jet pump efficiency increases with increasing pump area ratio up to a certain value and then pump efficiency decreases. It was found that maximum computed efficiency is 37.82 % at the pump area ratio of 0.271 and a pressure ratio of 0.317. In addition, the numerical results showed that the optimum relative length of mixing chamber is 5.48 and the optimum value for diffuser angle at which the efficiency is a maximum value is 5o. Experimental tests were conducted to study the effects of various geometrical and operational parameters on the performance of the jet pumps. A test rig was constructed using the optimum design from the numerical results. The physics of flow within axial-water jet pumps can be analyzed and optimized easily by using the CFD, 2D technique with a satisfactory accuracy in order to save computational time and cost. The CFD’s results were found to agree well with actual values obtained from the experimental results.

Literature Review on Different Factor’s That Affecting Jet Pump Performance

Literature Review on Different Factor’s That Affecting Jet Pump Performance

Flow Separation and Turbulence in Jet Pumps for Thermoacoustic Applications

The effect of flow separation and turbulence on the performance of a jet pump in oscillatory flows is investigated. A jet pump is a static device whose shape induces asymmetric hydrodynamic end effects when placed in an oscillatory flow. This will result in a time-averaged pressure drop which can be used to suppress acoustic streaming in closed-loop thermoacoustic devices. An experimental setup is used to measure the time-averaged pressure drop as well as the acoustic power dissipation across two different jet pump geometries in a pure oscillatory flow. The results are compared against published numerical results where flow separation was found to have a negative effect on the jet pump performance in a laminar flow. Using hot-wire anemometry the onset of flow separation is determined experimentally and the applicability of a critical Reynolds number for oscillatory pipe flows is confirmed for jet pump applications. It is found that turbulence can lead to a reduction of flow separation and hence, to an improvement in jet pump performance compared to laminar oscillatory flows.

On the performance and flow characteristics of jet pumps with multiple orifices.

The design of compact thermoacoustic devices requires compact jet pump geometries, which can be realized by employing jet pumps with multiple orifices. The oscillatory flow through the orifice(s) of a jet pump generates asymmetric hydrodynamic end effects, which result in a time-averaged pressure drop that can counteract Gedeon streaming in traveling wave thermoacoustic devices. In this study, the performance of jet pumps having 1-16 orifices is characterized experimentally in terms of the time-averaged pressure drop and acoustic power dissipation. Upon increasing the number of orifices, a significant decay in the jet pump performance is observed. Further analysis shows a relation between this performance decay and the diameter of the individual holes. Possible causes of this phenomenon are discussed. Flow visualization is used to study the differences in vortex ring interaction from adjacent jet pump orifices. The mutual orifice spacing is varied and the corresponding jet pump performance is measured. The orifice spacing is shown to have less effect on the jet pump performance compared to increasing the number of orifices.

Characterization and reduction of flow separation in jet pumps for laminar oscillatory flows.

A computational fluid dynamics model is used to predict the oscillatory flow through tapered cylindrical tube sections (jet pumps). The asymmetric shape of jet pumps results in a time-averaged pressure drop that can be used to suppress Gedeon streaming in closed-loop thermoacoustic devices. However, previous work has shown that flow separation in the diverging flow direction counteracts the time-averaged pressure drop. In this work, the characteristics of flow separation in jet pumps are identified and coupled with the observed jet pump performance. Furthermore, it is shown that the onset of flow separation can be shifted to larger displacement amplitudes by designs that have a smoother transition between the small opening and the tapered surface of the jet pump. These design alterations also reduce the duration of separated flow, resulting in more effective and robust jet pumps. To make the proposed jet pump designs more compact without reducing their performance, the minimum big opening radius that can be implemented before the local minor losses have an influence on the jet pump performance is investigated. To validate the numerical results, they are compared with experimental results for one of the proposed jet pump designs.

Jet pumps for thermoacoustic applications: Design guidelines based on a numerical parameter study

The oscillatory flow through tapered cylindrical tube sections (jet pumps) is characterized by a numerical parameter study. The shape of a jet pump results in asymmetric hydrodynamic end effects which cause a time-averaged pressure drop to occur under oscillatory flow conditions. Hence, jet pumps are used as streaming suppressors in closed-loop thermoacoustic devices. A two-dimensional axisymmetric computational fluid dynamics model is used to calculate the performance of a large number of conical jet pump geometries in terms of time-averaged pressure drop and acoustic power dissipation. The investigated geometrical parameters include the jet pump length, taper angle, waist diameter, and waist curvature. In correspondence with previous work, four flow regimes are observed which characterize the jet pump performance and dimensionless parameters are introduced to scale the performance of the various jet pump geometries. The simulation results are compared to an existing quasi-steady theory and it is shown that this theory is only applicable in a small operation region. Based on the scaling parameters, an optimum operation region is defined and design guidelines are proposed which can be directly used for future jet pump design.

A numerical investigation on the vortex formation and flow separation of the oscillatory flow in jet pumps.

A two-dimensional computational fluid dynamics model is used to predict the oscillatory flow through a tapered cylindrical tube section (jet pump) placed in a larger outer tube. Due to the shape of the jet pump, an asymmetry in the hydrodynamic end effects will exist which will cause a time-averaged pressure drop to occur that can be used to cancel Gedeon streaming in a closed-loop thermoacoustic device. The performance of two jet pump geometries with different taper angles is investigated. A specific time-domain impedance boundary condition is implemented in order to simulate traveling acoustic wave conditions. It is shown that by scaling the acoustic displacement amplitude to the jet pump dimensions, similar minor losses are observed independent of the jet pump geometry. Four different flow regimes are distinguished and the observed flow phenomena are related to the jet pump performance. The simulated jet pump performance is compared to an existing quasi-steady approximation which is shown to only be valid for small displacement amplitudes compared to the jet pump length.

Cavitating flow in annular jet pumps

Based on the experimental and numerical methods, the pump performance and inner flow details of annular jet pumps under three area ratios (cross sectional area ratio of throat and nozzle) were studied in the present paper. The cavity clouds forming at the shearing layer, recirculation center and throat inlet were captured via high speed video. The realizable k–ε turbulence model combined with mixture cavitation model was well validated by experimental results on the pump performance (pressure ratio and pump efficiency) and the static wall pressure distribution. When the annular jet pump works under the critical working condition, the pressure ratio and the pump efficiency experience a sudden drop. Simultaneously, the flow rate ratio and cavitation number keep constant regardless of the decreasing outlet pressure, since the main flow is filled with cavity clouds. Moreover, the inception and development of cavity cloud induced at the throat inlet were particularly studied in this paper. The cavitation in the throat experiences three stages (incipient, stable and unstable stage) before extending into the diffuser, in which the unstable stage signals the approaching of the critical working condition. The cavity cloud there fluctuates slowly and faintly, while it may suddenly expand over the whole throat and vanish immediately. When the cavity cloud extends into the diffuser with the closure place x/Dt<2.8 (Dt is the diameter of throat length), there is a low frequency cavity cloud surge. However, the surge disappears as the cavity cloud increases to the intermediate part of the diffuser. Additionally, based on imaging analysis method, the frequency characteristic of the cavity shedding in the diffuser was also studied. The shedding of cavity cloud in the diffuser experiences multiple periodicities when Lcav=3.25Dt (cavity length in diffuser), while there are two fundamental frequencies (58Hz and 6Hz) for Lcav=1.1Dt with the higher one corresponding to the shedding frequency. In the case of Lcav=3.25Dt, the detached cavity cloud in the diffuser is pushed downstream only by the re-entrant jet. However, the main flow plays an important role on accelerating the detached part downstream in the case of Lcav=1.1Dt.