Volume 3B: Fluid Applications and Systems最新文献

{"title":"Effects of Volute Cross-Sectional Area Distribution on Performance of Double-Suction Volute Pump","authors":"Szu Yung Chen, Lu Zhang, Yumiko Sekino, Hiroyoshi Watanabe","doi":"10.1115/ajkfluids2019-5251","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5251","url":null,"abstract":"\u0000 The following study describes the optimization design procedure of a double-suction pump. BASELINE pump is designed as inlet nozzle diameter 800 mm and impeller outlet diameter 740 mm. Each component of a BASELINE pump, impeller configurations, discharge volute, and the suction casing were determined by DOE (Design of Experiments) and sensitivity analysis. However, finite selected design parameters for each component are mostly restricted to the free surface design of the pump casing. In this study, the optimization method approach along with steady Computational Fluid Dynamics (CFD) is introduced to achieve the high efficiency request of a double-suction pump. To investigate the matching optimization of the impeller and discharge volute at design point, the full parametric geometry of discharge volute was developed referred to the BASELINE shape and Multi-Objective Genetic Algorithm NSGA-II (Non-dominated Sorting Genetic Algorithm II) was used. Optimization result shows that by increasing the volute cross-sectional area from the volute tongue till the circumferential angle 180 deg. provides lower loss. This is due to the improvement achieved for the better distribution of the velocity gradient within the volute. A validated unsteady computational fluid dynamics (CFD) was also employed to investigate the performance difference between optimized volute design and the BASELINE which correlated to the pressure fluctuation and secondary flow behavior inside the cross-sections from 80% to 120% of nominal flow rate. The result shows that the flow distortion in the streamwise direction is stronger with the BASELINE and sensitively affects the operation stability. This is due to the different secondary flow pattern in the cross-sections, hence demonstrating a design direction of desired volute cross-sectional shape for high-performance can be used in a double-suction volute pump.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121048659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Magnetic Journal Bearing Instability Issues in Supercritical CO2 Turbomachinery","authors":"Dokyum Kim, Seungjoon Baik, Jeong-Ik Lee","doi":"10.1115/ajkfluids2019-5349","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5349","url":null,"abstract":"\u0000 With the increasing emphasis on reducing the CO2 emission while improving power generation efficiency, new power cycles are being developed. One of those promising power cycles is a supercritical CO2 (S-CO2) power cycle. To generate over 10MW electricity with S-CO2 power cycle, a magnetic bearing can be a good option for the hermetic type turbomachinery. However, from several studies on the magnetic bearing, the instability issues under high density fluid and high speed operating conditions were repeatedly mentioned. The instability in the magnetic bearing was observed to be related to the fluid conditions, mostly pressure and density. Because of this issue, the magnetic bearing sometimes cannot maintain enough clearance for the rotor leading to physical contact and consequently damaging the system. Thus, these instability issues should be thoroughly studied and be resolved for the successful and steady operation of the power system. The instability due to fluid force around the rotating shaft can be modeled with the Reynolds lubrication equation. The steady lubrication force analysis model is developed based on this equation. The model results imply that the lubrication performance is quite sensitive to the thermal condition of the CO2 especially density gradient around the shaft. Based on the modeling results, an experimental system is designed to investigate the issue. To study the instability issues experimentally, an impeller of the operating S-CO2 compressor is removed and the discharge line is blocked. Therefore, the main instability factor in this experiment will be the interaction between the rotor and the bearing only. The shaft position can be measured with inductive sensors. The forces exerted from the electromagnet is calculated from the electric current data which is applied by the controller. From these experimental data, the lubrication force is calculated. These results are compared with the analytical lubrication model to verify the model. From this study, it is expected that it will be possible to define the unstable operating conditions and suggest the required magnetic bearing performance for S-CO2 conditions.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133899540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the Influence of Centrifugal Pump Inlet Flow Field Instability and Methods of Adjustment","authors":"B. Qian, Jin-Ping Chen, Peng Wu, Bin Huang, Dazhuan Wu","doi":"10.1115/ajkfluids2019-4687","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4687","url":null,"abstract":"\u0000 The quality of centrifugal pump inlet flow field is an important factor that affecting the performance of pump. Studies have proved that the vortex in the inlet area can also bring an extra flow instability to pump, which results in a hydro-induced vibration. This phenomenon is more common and significant in the pumps with an elbow tube, which is often applied to minimize installation size, before pump inlet. Therefore, it is necessary to look into the influence of inlet flow field instability on pump performance especially the vibration performance. The methods of adjusting pump inlet flow field is also worthy of being studied in the meantime. In this study, the influence of inlet vortex on the performance of centrifugal pump with an elbow inlet tube is investigated by means of CFD analysis. The flow is significantly affected when going through the elbow tube inlet and then turbulence is generated as a result, which enters the impeller at the next moment. The turbulence brings an asymmetrical flow condition at the impeller suction area, which can intensify pressure pulsation and hydro-induced vibration. In order to reduce the turbulence, two modifications on the elbow inlet tube are investigated in this study. A specially designed vane is deployed inside the inlet tube in the MOD1, and the MOD2 is added with two splitter vanes on the basis of the MOD1. The turbulent flow in the elbow inlet tube can be reordered as it is controlled by the vanes. The difference on pump performances that the inlet vane has made is specifically simulated and compared. The flow fields of the inlet tube influenced by the vane is also investigated on the vortex distribution and velocity vector distribution. The MOD1 has a generally smaller pressure fluctuation amplitude than the prototype in the impeller inlet area while the pressure fluctuation amplitude of the MOD2 in the impeller inlet area is stronger than the prototype. It is considered as a consequence of multiple effects, which are, the rise of velocity because of flow area replacement by the vanes making the flow field less stable as well as the wake flow induced by the vanes increasing the instability of the flow field. Therefore, although the flat vanes can help adjusting the flow field, their negative influences also act in the opposite way. It is worthwhile to find the balance between the benefits and the costs in flow field stability of installing adjusting vanes. The selection of parameter, number and installation position needs to be further investigated. The numerical results of the MOD1 are also validated through experimental investigations.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132783439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Method for Studying Bearing Gap Pressure Wave Development and Subsequent Performance Mapping of Externally Pressurized Gas Journal Bearings","authors":"Tom M. Lawrence, M. D. Kemple","doi":"10.1115/ajkfluids2019-4732","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4732","url":null,"abstract":"\u0000 In previous work, numerical methods were developed to determine the pressure waves (pressure distribution) in the bearing gap of round externally pressurized gas bearings (EPB’s) that were pressurized through porous liners (PL bearings) or through liners with rows of feedholes (FH bearings). When integrated and differentiated these pressure portraits yield the net hydrodynamic force (FH) between the shaft and the bushing and the mass flow rates through the bearing gap. These results successfully replicated force-deflection curves and mass flow rate data for experimentally tested prototype FH and PL bearings over a wide range of mass flow constriction and clearances. Subsequently the numerical study was expanded to a broader design space of clearance and mass flow compensation. Also, a bearing performance mapping method of mapping the normalized bearing load over the clearance-eccentric deflection plane was developed for different levels of mass compensation. These performance maps produced a very interesting result as they indicated certain areas in the design space of FH bearings where static instability (negative stiffness) would be encountered. This static instability was not observed in the experimental data but is noted in references as known to occur in practice. Because this numerical method is based on the development of pressure wave portraits, the FH pressure wave could then be “dissected” in the areas of the onset of static instability which gave much insight as to the possible causes of static instability. This initial work, then, was perhaps the first to predict where in design space static instability would occur and yield some insight via examination of the corresponding pressure waves as to the cause. The numeric techniques developed, however are in no way limited to non-rotating bearings but are extensible to rotating bearings. The method is also easily extensible to examination of any configuration of feedholes or orifices. Nor is it limited to parallel deflections but can yield results for unbalanced loads. The method is also not limited to round bearings but can be applied to any cross-section configuration of bearing gap cross section such as a 3 lobed bearing or a slotted 3 lobed bearing. Examination of the resulting pressure wave development patterns for different scenarios can be examined to garner insight as to the causes of differing performance that can be applied to alterations towards optimization. Thus sharing in detail the developed numerical method underlying these studies seems worthwhile.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114657746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characteristics of Swirl Angle in Pump Intake Flow Near the Minimum Inlet Submergence","authors":"Tajul Ariffin Norizan, Z. Harun, W. Mohtar, S. Abdullah","doi":"10.1115/ajkfluids2019-5053","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5053","url":null,"abstract":"\u0000 Swirling flow in pump sump intake has been the subject of discussion for the past decades due to the detrimental effects brought about by its existence. Among the effects of swirling flow are reduced pump efficiency, cavitation, excessive vibration and load imbalance at the pump impeller which are caused by hydraulic problems associated to swirling flow such as swirls and vortices. One of the remedial measures for preventing such occasion is by keeping the pump inlet submerged above a defined value known as the minimum inlet submergence. It is the minimum submergence required to reduce the probability of the occurrence of free surface vortices. However, this requirement may not be fulfilled in some situations due to on site conditions or operational restrictions. In this paper, an experimental study was conducted to investigate the characteristics of swirl angle in the pump intake flow when the pump inlet is submerged near the value of minimum inlet submergence. The ratio of pump submergence to the minimum submergence was varied between 0.8 to 1.2 with constant inlet Froude Number which referred to as submergence ratio. The strength of the swirl in the intake flow was determined by measuring the swirl angle which was accomplished using a swirl meter attached in the suction pipe. Measurements using Acoustic Doppler Velocimeter (ADV) was performed to capture the velocity profile in the intake sump. The swirl angle distribution across the range of submergence ratios was dominated by a subsurface vortex formed at the sump floor. As soon as the submergence was reduced below the minimum submergence, a free surface vortex emerged near the pump inlet and brought a swirl retardation effect to the swirl meter rotation resulting in a bigger fluctuation of the swirl meter reading. An anti vortex device (AVD) called the floor splitter commonly used to reduce vorticity at pump inlet was installed and its effect on the reduction of swirls and vortices was evaluated.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125963227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Investigation of the Flow Inside the Rotor Passage of an Axial Ventricular Assist Device","authors":"Huanguo Chen, Primož Drešar, B. Lynch, Paarth Sharma, Christopher G. Williams, J. Katz","doi":"10.1115/ajkfluids2019-5660","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5660","url":null,"abstract":"\u0000 Ventricular assist devices (VAD) are designed to provide circulatory support to patients suffering from advanced-stage heart failure. While not pulsatile, the advantages of continuous axial flow VADs include a compact size and low mechanical failure rate. However, being compact, they operate at high speed, resulting in adverse effects, such as hemolysis caused by high flow shear and thrombosis formation in stagnant regions are common and threaten the successful use of the device. While state-of-the-art computational fluid dynamics (CFD) is widely used in designing these devices, detailed high-resolution experimental measurements of the flow within them are not readily available in the literature. Such experimental data is crucial for understanding the flow inside the VAD and its interaction with blood cells as well as for validating the CFD predictions. The present study investigates the flow inside a 1:1 exact replica of a VAD – ReliantHeart HeartAssist5®. This 12mm diameter device consists of an inlet guide vane (IGV), a rotor and a stator. However, unlike in the real machine, the rotor is driven by a thin shaft that penetrates through the center of the IGV. Refractive index-matching is used to facilitate optical measurements. Hence, all the blades and housing of the pump are made of transparent acrylic. The working fluid is a mixture of water, sodium iodide and glycerin, which matches the refractive index of acrylic, and the kinematic viscosity of blood. Performance tests have been carried out at speeds ranging from 7000 to 9000 RPM. Trends of the results are consistent with those of the actual machine. While scaled data for the pressure rise across the rotor at different speeds collapse, the total head rise across the entire machine does not. High-resolution 2D PIV measurements with vector spacing of 30μm have been conducted in meridional planes of the rotor passage at several blade orientations. They have been performed at 8000RPM and flowrate of 4.5L/min, consistent with physiological requirements. They show that near the rotor front end, the flow in the tip region is dominated by the tip leakage vortex (TLV), associated blockage effects, and very high turbulence level. The upstream end of this domain remains aligned with the leading edge, implying that blades persistently dissect the remnants of a previous TLVs. Interaction of the hub boundary layer with the blades also generates secondary flows. Downstream of the helical section of the rotor, the axial flow is high near the hub and low in the outer part of the passage due to leakage flow-related blockage. Hub boundary layer separation occurs upstream of the stator, generating a large circumferential vortex that occupies nearly half of the rotor span. The complexity of the flow structure and turbulence in this machine would be a challenge to model.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115175841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Pressure Pulsation in the Stages of an Electric Submersible Pump at Best Efficiency Point Under Various Speeds","authors":"Dhanasekaran Arumugam, Kumaraswamy Sivasailam","doi":"10.1115/ajkfluids2019-5081","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5081","url":null,"abstract":"\u0000 Fluctuating pressures can induce vibration in the Electric Submersible Pump (ESP) and severely affect the pump components. The installation depths of ESP systems are varying from a few meters to several hundred meters. Once installed ESPs are not accessible for diagnostic measurement and maintenance activity, so it becomes necessary to obtain detailed information of mean and fluctuating pressures to attain an optimal pressure distribution inside the pump. In this paper the results obtained from an experimental investigation of stage-wise pressure pulsation at Best Efficiency Points at various speeds are presented. Tests were conducted on a five stage ESP having impellers of 121 mm diameter and 14 mm width at outlet with impeller of 8 vanes and a diffuser-return channel of 6 vanes which delivers 7 lps (litres per second) and develop 60 m total head at various speeds. Unsteady pressure signals were captured by mounting piezoresistive transducers at each stage of ESP. Captured pressure signals were converted into frequency domain to analyze the characteristics of pressure pulsation. The results have indicated that the maximum amplitude of pressure pulsation was obtained at the highest operating speed setting of 60 Hz at stage 4. The normalized frequency at which this amplitude was maximum was highest at stage 2 at all the speeds.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129512372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Stator Geometry on the Performance of a Positive Displacement Hydraulic Turbine","authors":"Arihant Sonawat, Jin-Hyuk Kim, Seung-Jun Kim, Young-Seok Choi, Hyeon-Mo Yang, Yong-Kab Lee, Kyungmin Kim","doi":"10.1115/ajkfluids2019-5283","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5283","url":null,"abstract":"\u0000 Positive displacement turbine (PDT) is a special class of hydraulic turbine which finds its usage in the applications involving very low flow rates with high heads and very low specific speeds. In the present case, a PDT was designed and developed to replace the pressure differential control valve (PDCV) and to harness the unused differential pressure energy from the water supply pipeline system. The turbine was designed considering the on-site available head and flowrate. The rotors were twisted to damp the fluctuations in pressure, flow rate and torque. The primary objective of the present study was to analyze the effect of the stator shape on the performance of PDT using Computational Fluid Dynamics approach. The governing equations of the fluid flow were solved using an unsteady approach to capture accurately the pulsating nature of the flow using ANSYS CFX v17.1. Initially a circular stator turbine was used for transporting the working fluid to and from the turbine rotors and later the effects of square and rectangular shaped stator designs were also checked. It was observed that the performance of the PDT slightly improved with rectangular and square stators in terms of hydraulic efficiency than with circular stator with low flow fluctuations.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132544611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of Rotating Speed on Performance of Electrical Submersible Pump","authors":"Yang Yang, Lingjiu Zhou, W. Shi, Chuan Wang, Wei Li, R. Agarwal","doi":"10.1115/ajkfluids2019-5093","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5093","url":null,"abstract":"\u0000 High speed rotating pump is the current trend in pump’s development and application, which has the advantages of compact size and energy-saving features. The electrical submersible pump, typically called an ESP, is an efficient and reliable artificial-lift method for lifting moderate to high volumes of fluids from wellbores, which have been wildly used for oil or groundwater extraction. To verify the similarity of pump performance under different rotating speeds, a typical ESP is selected as the model pump. By employing the numerical simulation and performance testing methods, the external performance characteristics and internal flow fields under different rotating speeds of the pump are studied. The entire computational domain is established by two stages ESP, and then meshed with the high-quality structured grid based on the Q-type and Y-type block topology. Grid sensitivity analysis is carried out to determine the appropriate mesh density for mesh independent solution. SST k-ω turbulence model with standard wall function in conjunction with Reynolds-Averaged Navier-Stokes (RANS) equations is used to solve the steady flow field. The results show that the increase in the rotating speed could increase the ESP’s head significantly. ESP’s external characteristics under different speeds meet the similar conversion rule quite well. In addition, the flow field distributions in the main flow components of the pump have great similarity at different rotating speeds. The experimental test results for a prototype show good agreement with the simulation results, including the pump’s head, efficiency and axial force. This paper provides a data set for further understanding of the effects of rotating speeds on ESP’s performance and inner flow fields.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121245060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D Modeling of Unsteady Flow Characteristics in ALIP Pump","authors":"R. Zhao, Heng Miao, Desheng Zhang, Huang Jun, Xiongfa Gao","doi":"10.1115/ajkfluids2019-5183","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5183","url":null,"abstract":"\u0000 Annular linear induction pump (ALIP) is an ideal type of pump applied as the nuclear coolant pump for the sodium-cooled faster reactor (SFR). However, the operation will suffer from serious unstable problems when the pump size is increased and run at certain working conditions. A 3d numerical model of an ALIP based on the Finite Element method is built in this work to study the flow instability in the pump channel. The results show that the model can accurately predict the pump head at different working flow rate and some common phenomena, such as double supply fluctuation (DSF) and low frequency fluctuation. The results under unstable condition show that the liquid sodium in pump channel will separate in term of the outer stator position. Reversed flow and vortices always occur in the channel between two outer stators because of the non-uniform magnetic field in the azimuthal direction. Meanwhile the unstable flow is first presented in the meridian plane near the outer duct surface. Finally, a wave-like swing of the flow is presented at the rear of the unstable flow region, resulting in low frequency fluctuation in pressure.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131204980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}