Volume 3B: Fluid Applications and Systems最新文献

{"title":"Prediction of Aerodynamic Noise for Centrifugal Fan of Air-Conditioner by Tetra-Prism Grids","authors":"T. Iwase, D. Sato, H. Obara, Y. Yamade, C. Kato","doi":"10.1115/ajkfluids2019-4638","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4638","url":null,"abstract":"\u0000 We calculated fan performance and aerodynamic noise in the centrifugal fan of air conditioner by large eddy simulation (LES). In this study, we investigated simulation technology employing tetra-prism grids for practical usefulness. Tetraprism grids are easier to generate than hexahedral grids. We employed the numerical simulation code FrontFlow/blue (FFB) throughout the LES. First, we proposed a design method for tetra-prism grids. The design method featured a predicted boundary layer thickness that was the same as the thickness of a prism layer. Next, we compared calculated results for the 13 million grids, 107 million grids and 860 million grids to investigate the grid number influence on fan performance and aerodynamic noise. We confirmed that calculated results for larger number of grids was more accurate than smaller number of grids. We also confirmed that calculated results simulated streaks well and the number of streaks increased in the order of the increasing number of the grids. The proper simulating of the streaks therefore contributed to getting better calculated results. As a result, we confirmed that using the tetra-prism grids was practical in the actual development of fans.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"2 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":"122363742","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":"Effects of the Circulating Jet Flow on the Suction Flow Field and Cavitation in a Canned Motor Pump","authors":"Laizuo Chen, Minguan Yang, Wei Cui, B. Gao, Ning Zhang, Dan Ni","doi":"10.1115/ajkfluids2019-4879","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4879","url":null,"abstract":"\u0000 Cavitation is a general phenomenon in centrifugal pumps. When the inlet pressure near the leading edge of the blade is lower than the saturated pressure, cavitation would develop in the impeller. As cavitation occurs, the pump head will drop rapidly and the pump efficiency will decrease. In addition, severe vibration and noise will be induced. Cavitation performance is considered as an important factor in many industrial applications, and affected by various conditions.\u0000 The canned motor pump is a special type of non-seal centrifugal pump. The pump and motor are integrated. In order to cool the motor and lubricate the bearing during the operation, a portion of fluid, called the circulating flow, is withdrawn from the impeller outlet, and then flows along the cooling circle within the motor. Finally, the circulating fluid moves through the hollow shaft and merges with the main suction flow near the impeller inlet, which can be defined as the circulating jet flow. The jet flow will alter the uniform velocity distribution at the impeller inlet as its direction is opposed to the main suction flow. Consequently, it is expected that the cavitation performance of the pump will drop drastically. It is necessary to analyze the effect of the jet at the pump inlet on the cavitation performance.\u0000 In this paper, in order to illustrate the jet flow on the pump performance, a numerical simulation method is applied to depict the fluid flow field and cavitation performance of a canned motor pump. For the turbulent model, the standard k-ε turbulent model is adopted. To capture the cavitation performance of the pump, the Zwart-Gerber-Belamri cavitation model was used to investigate the steady cavitation flow through the entire flow channel.\u0000 It can be seen from the numerical results that the internal jet flow formed by the coolant circulation has a significant effect on cavitation performance. At the pump inlet, the velocity field is divided into three regions: the internal jet flow region, the main-stream region, and the backflow region. The internal jet presents a typical submerged jet structure and its existence results in the non-uniform inlet flow distribution. For the jet flow, it extends to the pump inlet and exhibits an asymmetric characteristic. The static pressure near the impeller inlet with the internal jet is drastically reduced compared to the case without the internal jet structure, and a local low-pressure region occurs around the outlet of the jet nozzle. The cavitation performance of the pump with the internal jet drops obviously. At the off-design condition, the cavitation performance of the pump is seriously degraded. From quantitative data, it indicates that the NPSH3 increases by more than 1.51 times compared with that of the original impeller under design condition. The cavitation inception occurs on the suction side of the leading edge of the impeller near the hub, and then cavitation also occurs near the outlet of the jet nozzle. Finally,","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"56 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":"115900802","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 and Analysis of the Flow Field Induced by a Symmetrical Suction Elbow at the Pump Inlet","authors":"S. Muntean, A. Bosioc, I. Drăghici, L. Anton","doi":"10.1115/ajkfluids2019-5066","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5066","url":null,"abstract":"\u0000 The pump inlet casing deflects the fluid flow from the inlet pipe, mainly arranged normally to the axis, into the axial direction. The pump inlet casing can take a large variety of geometrical shapes from curved pipes to three-dimensional elbows. The hydrodynamic field induced by symmetrical suction elbow (SSE) at the pump inlet is experimentally investigated in order to quantify it effects at the pump inlet. The pump test rig and the experimental setup are detailed. A SSE model is installed at the pump inlet. Laser Doppler Velocimetry (LDV) measurements are performed on the annular cross section located at the pump inlet. As a result, the map of the velocity field is determined quantifying the non-uniformities induced by SSE. Next, the full 3D turbulent numerical investigation of the flow in the SSE is performed. The numerical results on the annular cross section are qualitatively and quantitatively validated against LDV data. A good agreement between numerical results and experimental data is obtained. The hydrodynamic flow structure with several pairs of vortices is identified examining the vorticity field. However, two pairs of vortices with largest contribution to the flow non-uniformity are examined. Three parameters are considered to quantify the evolution of each vortex center: two geometrical quantities (e.g. the radial and angular coordinates) and one hydrodynamic (the magnitude of vorticity). The largest values of the vorticity magnitude are identified in the center of both vortices located behind the shaft. The 3D distribution of the vortex core filaments is visualized. As a result, the 3D geometry of the SSE and the pump shaft are identified as the main sources of the flow non-uniformity at the pump inlet. This deep analysis of the 3D flow field induced by the SSE paves the way towards an improved geometry with practical applications to real pump and pump-turbines.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"149 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":"115743784","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 Study on the Flow Field Analysis and Optimization of Turbine in Supercritical Compressed Air Energy Storage","authors":"Meng Wang, Jianqiang Deng, Yang He, Haisheng Chen, Yujie Xu","doi":"10.1115/ajkfluids2019-4849","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4849","url":null,"abstract":"\u0000 Supercritical compressed air energy storage system requires high turbine efficiency over a wide working range at both the design-point and off-design point. The operating range of the turbine is often limited by the occurrence of flow instability, such as distinct vortex and load deterioration. In specific situations, the development of aerodynamic instabilities at low inlet pressure operating conditions can lead to lower turbine efficiency, even lead to turbine choke, limiting the wide operating range of the turbine. Specifically, the high-pressure stage turbine of the expander, namely the first stage turbine, will not only bears a sharp change of inlet pressure but also experiences the maximum and variable pressure drop. In this paper, Real Gas Property (RGP) file for supercritical air is used for simulations. The CFD method and RGP file are validated by the turbine in the NASA report. A detailed 3D CFD analysis is performed for the preliminary designed first stage turbine under variable inlet pressure. With the purpose of improving the aerodynamic performance of the first stage turbine under extreme working conditions, a series of simulations are conducted to examine the effects of the IGV parameters (i.e. different types of IGVs, the nozzle-impeller radial gap distance and the nozzle blade installation angle) and blade thickness, which led to the optimization in overall turbine stability. The results show that IGV TC-2P have good aerodynamic performance, and the matched rotor can achieve an isentropic efficiency of 80% under off-design working conditions. The optimal blade installation angle blade is 35°. And there exists an optimal nozzle-impeller radial gap distance Δr. The turbine efficiency obtains a maximum value at Δr = 5 mm. In all cases for blade thickness, the different configurations have a significant change in inlet total pressure of 4.5 MPa compared to the design pressure of 7 MPa. The maximum efficiency is reached at the ellipse ratio is 1:1 for Case-2. The results of the optimal IGV TC-2P performance optimization is essential to improve the isentropic efficiency at low inlet pressure.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"91 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":"121678720","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":"A Numerical Study of Turbulence Model and Rebound Model Effect on Erosion Simulations in an Electrical Submersible Pump (ESP)","authors":"Haiwen Zhu, Jun Zhang, Jianjun Zhu, R. Rutter, Hong-quan Zhang","doi":"10.1115/ajkfluids2019-5538","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-5538","url":null,"abstract":"\u0000 Sand production is one of the most serious problems of electrical submersible pumps (ESPs). It is important to predict erosion rate and pump life under sand flow condition. However, erosion experiments on centrifugal pumps are difficult, expensive and time-consuming. Besides, the erosion on pump blades and shrouds are hard to be quantified. It is difficult to measure or scan the thickness of an inside flow channel. Therefore, computational fluid dynamic (CFD) method is a convenient way to forecast erosion failures of the pump. Although various erosion simulations were carried out for simple geometries, including pipelines, elbows, tees, and etc., erosion simulation methodology in a turbomachinery geometry should be carefully evaluated. Therefore, the effect of different turbulence models and rebound models are investigated in a 3-stage mixed type ESP by ANSYS Fluent Discrete Phase Model (DPM) simulations. The erosion rate is calculated and particle impact parameters are extracted by a User Define Function (UDF). Preliminary erosion simulation methodology recommendations were given in this study.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"106 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":"121527670","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":"Multi-Objective Optimization of a High Specific Speed Centrifugal Volute Pump Using 3D Inverse Design Coupled With CFD Simulations","authors":"Luying Zhang, Gabriela Dávila, M. Zangeneh","doi":"10.1115/ajkfluids2019-4676","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4676","url":null,"abstract":"\u0000 This paper presents three different multi-objective optimization strategies for a high specific speed centrifugal volute pump design. The objectives of the optimization consist of maximizing the efficiency and minimizing the cavitation while maintaining the Euler head. The first two optimization strategies use a 3D inverse design method to parametrize the blade geometry. Both meridional shape and 3D blade geometry is changed during the optimization. In the first approach Design of Experiment method is used and the efficiency computed from CFD computations, while cavitation is evaluated by using minimum pressure on blade surface predicted by 3D inverse design method. The design matrix is then used to create a surrogate model where optimization is run to find the best tradeoff between cavitation and efficiency. This optimized geometry is manufactured and tested and is found to be 3.9% more efficient than the baseline with little cavitation at high flow. In the second approach the 3D inverse design method output is used to compute the efficiency and cavitation parameters and this leads to considerable reduction to the computational time. The resulting optimized geometry is found to be similar to the more computationally expensive solution based on 3D CFD results. In order to compare the inverse design based optimization to the conventional optimization an equivalent optimization is carried out by parametrizing the blade angle and meridional shape. Two different approaches are used for conventional optimization one in which the blade angle at TE is not constrained and one in which blade angles are constrained. In both cases larger variation in head is obtained when compared with the inverse design approach. This makes it impossible to create an accurate surrogate model. Furthermore, the efficiency levels in the conventional optimization is generally lower than the inverse design based optimization.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"63 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":"114525990","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 Design of a Partial-Support Axial Blood Pump","authors":"Guangmao Liu, Donghai Jin, Mengyu Wang, X. Gui","doi":"10.1115/ajkfluids2019-4916","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4916","url":null,"abstract":"\u0000 Partial-support is the main support mode for “less sick” patients with severe heart failure. But there were fewer partial-support blood pumps for clinical use. An implantable partial-support axial blood pump was developed for heart failure patients. To gain better hemolytic performance and lower pump thrombus risk, the rotor blades were extended to the contractive section of the rotor hub while cone-bearing was adopted. The hydraulic and hemolytic performance of the blood pump was simulated and analyzed by computational fluid dynamics (CFD) method. The flow velocity, hydraulic efficiency, exposure time, scalar shear stress (SSS) and hemolytic performance of the axial blood pump was analyzed. The numerical results showed that the axial blood pump could produce a 1–8 Lpm flow rate with a 54.7–186.7 mmHg pressure head when the pump rotating from 9000 to 13000 rpm. The hydraulic efficiency and SSS distribution corresponded with the typical performance of a blood pump. The mean hemolysis index of the blood pump calculated by the Giersiepen’s model was 5.0 × 10−5%. After extending the rotor blades to the contractive section of the rotor hub, the spiral flow at the inlet of the rotor impeller was reduced. Hemolysis in the blood pump was improved because the exposure time was reduced and the blood damage caused by SSS was reduced.. The designed blood pump satisfies the clinical requirements of partial-assist for less-sick heart failure patients.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"3 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":"128930918","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":"Effects of Splitter Vanes on the Performance and Pressure Pulsation in a Centrifugal Pump","authors":"Chao Li, B. Gao, Ning Zhang, Dan Ni","doi":"10.1115/ajkfluids2019-4878","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4878","url":null,"abstract":"\u0000 Two types of arrangement of splitter vanes at the outlet of a centrifugal impeller is proposed in this paper, that is, staggered vanes and splitter vanes. By means of CFD, the effects of different vanes arrangement schemes on the performance and pressure fluctuation characteristics of the centrifugal pump are compared. The influence mechanism of different schemes is explored based on the fluid flow field analysis. The results show that, compared with ordinary impellers, when the short vanes are 10 degree offset to the suction side of the main vanes, staggered vanes impellers cause the pump head and efficiency to decrease, while the amplitude of pressure pulsation at blade passing frequency (BPF) is reduced by 28% compared with that of the ordinary impeller under the design condition. In the splitter vanes scheme, the pump head and efficiency increased, however the efficiency increased more significantly under the large flow rate condition. The amplitude of pressure fluctuation at BPF is decreased by 14% compared with that of the ordinary impeller under the design condition. The existence of short vanes in both schemes changes the wake flow structure downstream the impeller vanes and tends to weaken the pressure pulsation induced by the rotor-stator interaction (RSI) phenomenon. The results can provide a reference for optimized design of the low vibration and less noisy pumps.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"92 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":"127060667","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 Interface Condition on the Hydraulic Performance of a Pump-Turbine at Various Guide Vane Opening Conditions in Pumping Mode","authors":"J. Suh, Seung-Jun Kim, Young-Seok Choi, Jin-Hyuk Kim, W. Joo, Jungwan Park","doi":"10.1115/ajkfluids2019-4800","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4800","url":null,"abstract":"\u0000 Nowadays, pumped-storage power stations require high flexibility and reliability in operation under off-design conditions, especially in the pump mode. When a pump-turbine operates under various part load conditions in pump mode, highly dynamic phenomenon such as stationary vortex and rotating stall occur. Therefore, the performance characteristics in pump mode are vital for the safe and effective operation. A number of studies have been conducted to investigate the flow characteristics in turbine or pump mode under different GVOs through numerical simulations. However, the studies about influence of the position of interface and interface condition on the pump characteristics of pump-turbines are not completely clear.\u0000 In this paper, the three-dimensional steady and unsteady Reynolds-averaged Navier–Stokes equations were solved for a detailed analysis of the influence of interface conditions with various guide vane opening conditions in pump mode. To ensure the reliability of the numerical analysis, the numerical results were validated in comparison with the experimental data.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"26 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":"126699362","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":"The Effects of Multiphase, Multi-Viscosity Fluids on Axial Thrust and Cooling Flow Performance of a Canned Motor Pump","authors":"Eric S. Conaway, J. Matos, Ryan Mesiano","doi":"10.1115/ajkfluids2019-4829","DOIUrl":"https://doi.org/10.1115/ajkfluids2019-4829","url":null,"abstract":"\u0000 A canned motor pump for technology demonstration in subsea oil and gas systems was tested to provide data to understand the design, modeling and performance characteristics of a canned motor pump operating in multiphase flow. This paper discusses the impact of multiphase flow and fluid viscosity on axial thrust and motor cooling flow characteristics.\u0000 The technology demonstrator is a two-stage, low specific speed (Ns∼550) centrifugal pump designed to deliver 140 gpm at 600 feet of head at 3930 rpm. The 61 hp canned motor is cooled by a small portion of the pump discharge fluid, which is drawn downward through the motor by pump out vanes on the hub of the second stage impeller.\u0000 The multiphase test loop is equipped for both water and light oil operation in low pressure and ambient temperature conditions. Testing occurred over a range of conditions to simulate varying fluid properties and operating scenarios. Shaft rotational speed varied between 2000 and 4250 rpm with pump liquid flow rates from 25 to 250 gpm. These operating scenarios were repeated for both water and light oil (∼2 cP) with multiphase flow ranging from 0–20% gas volume fraction (GVF) using injected air.\u0000 Testing results indicate a detectable impact from the different fluids and GVF’s tested, which can be related to features such as the second stage impeller pump-out vane and regions within the motor cavities. In water-air tests, increasing GVF led to the following: motor input power reduced by 5%; axial thrust increased by 100%; motor cooling fluid temperature rise increased by 100%; and pressure rise in the second stage pump out vanes reduced by 30% - directly impacting motor cooling flow rate, temperature rise, and axial thrust. In the oil-air tests, multiphase flow showed similar tendencies with reduced magnitude. Notably, the effects due to air injection do not appear at GVF below 15% with oil-air mixtures, unlike water-air tests which demonstrated effects across all GVFs.\u0000 The test results provide insight into the behavior of variable viscosity, multiphase flow in the canned motor pump cooling passages, as driven by the second stage impeller pump out vanes. These observed characteristics can be used to design flow control features and evaluate operational impacts, while the performance data obtained can be used to assess the behavior of flow models for this application.","PeriodicalId":270000,"journal":{"name":"Volume 3B: Fluid Applications and Systems","volume":"54 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114038339","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}