bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Piston Engine for Marine Vehicle Propulsion
Authors: Asfar Khaled , Al-Smadi Eyad 
Published: November 2019

Abstract
This paper describes an environment friendly propulsion system with negligible noise. The Propulsion system is based on a novel engine called a water piston engine. All moving parts in the classical internal combustion engine are eliminated; the piston, connecting rod, and crankshaft. Also, cams and follower valves are replaced by solenoid valves which inject compressed air into the cylinders. A water column in the cylinder is used to replace the metallic piston. The water column itself inside the cylinder acts as a piston. This Water Piston Engine is powered by pressurized air only. So, a pressure vessel is used to store compressed air. The Pressure derived from the compressed air tanks is directly used in providing thrust by pushing the water out of the cylinder through a 90-degree elbow as a water jet. When the water is ejected from the cylinder and the air pressure inside the cylinder decreases to near atmospheric, the water that surrounds the engine fills the cylinder. Four cylinders are used; each two cylinders are fired simultaneously in order to maintain thrust.
This system uses an Arduino microcontroller unit to deal with how much time the pressurized air is needed to discharge the cylinder and to switch the airflow between the engine cylinders. Several field tests have been made in a lake. The experimental data were compared to the theoretical based data in addition to simulate this model using Ansys fluent. The advantages of this novel engine over internal combustion engines are clarified. Videos of the experiments are recorded.
The Effect of Model Parameters on CFD Simulation of a Thermosyphon
Authors: Wang Huiyu , Walters D. Keith , Walters Keisha B. 
Published: November 2019

Abstract
Both numerical and experimental studies have previously been carried out to investigate the heat transfer performance of the two-phase closed thermosyphon (TPCT). This paper investigates the performance of a commercially available computational fluid dynamics (CFD) solver (Ansys FLUENT) to predict the complex flow behavior of TPCTs, with special focus on modeling of the mass transfer phase change process. The present study uses four different sets of mass transfer coefficients for condensation and evaporation within a previously documented phase change model to determine their impact on the simulation results. The mass transfer coefficients effectively control the rate of transfer from liquid to vapor phase during evaporation and vice versa during condensation. The choice of coefficients is assumed to represent a balance between numerical accuracy and stability. A baseline simulation is performed for which both the evaporation and condensation coefficients are equal and set to default values. Three additional simulations vary the magnitude of the coefficients and adopt relative values based on density ratio following a recommended method that has been previously found to be effective for these simulations. Initial results show that the case with the highest coefficient of evaporation and coefficient for condensation based on the density ratio is in good agreement with available experimental data of overall thermal resistance of the TPCT., with predictive capability degrading as the values of the coefficients are reduced. Additionally, the 3D CFD models implemented in this study appear to successfully predict the phase change process and vital flow behavior inside the TPCTs, at least in a qualitative sense.
Analysis of Angular Velocities, Surrounding Air Pressure and Velocities of Various Designed Micro Vertical Axis Savonius Wind Turbines by the Computational Fluid Dynamics (CFD) Method
Authors: Manosroi W. , Tangtrakool T. , Lhaosornthong C. 
Published: November 2019

Abstract
The objective of this study is to analyze angular velocities, surrounding air pressure and velocities of various micro vertical axis Savonius wind turbine prototypes by the Computational Fluid Dynamics (CFD) method. The angular velocities of turbines are the basic parameters for determining the major parameters of the wind turbines, such as efficiency, torque, power and electricity etc. Eight models of the micro vertical axis Savonius wind turbine made of acrylic were designed by varying three parameters including the turbine distance between the pivot point and the tip, the distance between the apex curvature and the center plane curvature and the cross section types (circular, square, triangular and trapezoid). The eight models were divided into three groups including two models (B1, B2) with two different cross section types (triangle and rectangular) in the first group, three models (C1, C2, C3) with three different distances from the curvature tip to the centerline of 110, 85 and 40 millimeters in the second group and three models (D1, D2, D3) with different distances between the pivot point and the tip in the third group. Then, the angular velocities, the surrounding air pressure and velocities of the micro vertical axis Savonius wind turbine at the five wind speeds at 5.59, 7.67, 9.76, 10.45 and 11.84 m/s were measured and evaluated by the ANSYS program. The simulation by the CFD method of the angular velocities of the designed wind turbines was compared with the experimental results. Some discrepancies due to the absence of friction in the CFD results were observed. However, discrepancies between the simulation and the experimental results were decreased when the wind speed was increased due to the increase of torque and force in the experimental results which has overcome the turbine core friction. It has indicated that at the highest wind speed (11.84 m/s), the designed micro vertical axis Savonius circular cross section wind turbine with the curvature of the distance from the apex curvature to the center plane at 110 millimeters gave the highest turbine angular velocity of 441 rpm. At this highest turbine velocity by the CFD simulation, the high surrounding air pressure was not the smallest and the low turbine surrounding air pressure area was not the largest. This might be due to the effect of the suitable apex curvature distance to the center plane causing the efficient air flow to overcome the effect of the surrounding air pressure. The wind turbine of the second group gave the highest angular velocities followed by the first and the third group. These designed micro vertical axis Savonius wind turbines can be used as a preliminary model for the design and construction of the micro wind turbine to generate electricity at low wind speed region, such as Thailand.
Numerical Investigation of Tip Leakage Vortex Cavitation in Axial Waterjet Pump With Different Tip Gap Sizes
Authors: Xu Shun , Ji Bin , Long Xinping , Qian Zhongdong , Li Guibin , Zhou Jiajian 
Published: November 2019

Abstract
The flow field in the tip region of the axial-flow waterjet pump is very complex. Although it has been studied for many years, many relevant phenomena have still been a puzzle. In present paper, many detailed data on instantaneous inner structures of the tip leakage flow and evolution of the tip leakage vortex cavitation with different tip gap sizes are offered. The numerical simulation has been conducted by using SAS turbulence model and ZGB cavitation model to understand the cavitation-vortex interaction mechanism. The predicted cavitation performance exhibits a reasonable agreement with the experimental results. Based on the illustration, with the impeller tip gap size decreasing, the cavitation area in rotating region gradually decreases. The cavitation development enhances vorticity production in an axial-flow waterjet pump. Vortices are mainly located at the impeller tip leakage region. The analysis of the relative vorticity transport equation indicates that the baroclinic torque term and the vortex dilation term have significant effects on cavitation, the main contributor to vortex generation is the vortex dilation term. In addition, in the impeller tip region, the effect of viscous diffusion term cannot be ignored, and the cavitation area has a larger amplitude of pressure pulsation.
Experimental Study on Abrasion and Cavitation Resistance of Non-Metallic Coating Materials for Pump
Authors: Liu Hou-lin , Cao Man-hui , Chen Jie , Wang Yong , Wang Cheng-bin 
Published: November 2019

Abstract
The protection of the flow-passage components of pump by using coating is an important method to increase wear resistance. This paper aims at examining abrasion resistance and cavitation erosion resistance of three typical non-metallic coating materials for pump including epoxy resin mortar, composite resin mortar and polyurethane. A wear-resistance test bench was built, using ultrasonic vibrating air eroding machine. Meanwhile, the main relative raw materials and formulas were introduced. The results indicate that: (1) The accumulated volume reduction of abrasion of composite resin mortar changes in an oblique waveform, and its abrasion resistance is better than that of epoxy resin mortar in a short period of time. The wear rate of epoxy resin mortar and composite resin mortar is higher than that of polyurethane. The total wear volume of epoxy resin mortar, composite resin mortar and polyurethane is decreased by 8.74%, 9.89% and 0.58% respectively within 30h of anti-wear test time; (2) The accumulated volume reduction of cavitation erosion of epoxy resin mortar is proportional to the time. In anti-cavitation erosion test time of 26 h, the erosion volume of composite resin mortar, polyurethane and epoxy resin mortar cavitation is reduced by 0.44%, 0.29% and 0.35%, respectively. It shows that cavitation erosion resistance of three coating materials is similar, while polyurethane materials have the best abrasion resistance.
Effect of Rotating Speed on Performance of Electrical Submersible Pump
Authors: Yang Yang , Zhou Ling , Shi Weidong , Wang Chuan , Li Wei , Agarwal Ramesh 
Published: November 2019

Abstract
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.
Assessment of Noise Signature for a Cavitating Centrifugal Pump
Authors: Stephen Christopher , Sivasailam Kumaraswamy 
Published: November 2019

Abstract
In recent days, sophisticated instruments have emerged to obtain an online measurement of performance parameters from centrifugal pump of different kinds and the signals can be directed to the hands of pump user through mobile application. With this in mind, a centrifugal pump of low specific speed was chosen for cavitation studies from 80% to 120% of flow rate and for three different speeds. An assessment was carried out for cavitation noise signature from those operating condition of pumps. The result of cavitation noise based on peak magnitude as well as average of noise revealed a nature and it depends on the flow rate with respect to nominal flow rate. The noise envelope for the flow rate at best efficiency and above was having similar trend whereas at flows less than duty point it was totally different. So the criteria for finding the deviation in noise cannot be uniform for all flow rates. In this paper, the method adapted was to impose a trend line to the measured cavitation noise information to find out the deviation with respect to normal operating condition. It was concluded that detection of abnormality in pumps due to cavitation effects requires the operating condition to be diagnosed first and the proper criteria for deviation in noise has to be imposed.
Evaluations of Shape Parameter of Groove for Reducing Noise Generated From Rotating Tires
Authors: Ishiyama Junya , Fujii Kozo , Asada Kengo , Sekimoto Satoshi , Koishi Masataka , Ikeda Toshiyuki 
Published: November 2019

Abstract
Acoustic fields obtained by large-eddy simulations around a rotating tire with the grooves are investigated to clarify the relationships between the shape parameters of the grooves and the directivity of noise sound. To acquire acoustic field around the rotating tire, the large-eddy simulations using the sixth-order compact finite difference scheme and the tridiagonal filter are performed. The sixteen cases including the non-groove case are considered in the present study. To evaluate the acoustic noise from the groove, the sound pressure level (SPL) of each point is computed, and the difference between the cases with and without the groove is investigated. The obtained Results indicate that the width at the opening side of the groove strongly impacts on the acoustic field, and the acoustic noise is reduced as the width at the opening side increases. Additionally, the acoustic noise is reduced as the width at the bottom side increases. However, the depth and the area of the groove do not have a strong relation to the acoustic field. In the viewpoint of the noise directivity, larger the widths at the opening side and the bottom side, and the angle between the bottom and the side wall reduce the acoustic noise on the side of the rotating tire, while that in front of the tire increase. These results provide new insight into our understanding the mechanism of noise generated from the rotating tire with grooves and may help to make intelligent design for noise reduction.
Measurements of Dimension and Morphology of Solid Particles Volume With Digital In-Line Holography
Authors: Wang Yijie , Chen Jun 
Published: November 2019

Abstract
Digital in-line holography (DIH) has been applied to measure the 3D position of objects in a variety of applications, including bubbles and droplets in multi-phase flows, tracking particles in turbulence flows, etc. In addition to the 3D position, the morphology and dimension of the individual particles can also be extracted from the recorded hologram. In this study, a lens-less digital in-line holography setup is applied to measure the morphology and size of three kinds of solid particles (Wollastonite Powder, Pearl Mica Powder and Solder Powder), whose sizes range from several to hundreds of micrometers. The statistics of equivalent diameter, aspect ratio and circularity are introduced to describe the morphology and dimension of each kind of particles. Microscopic images of the particles are taken to verify the accuracy of measurements with DIH. The results measured from DIH are in good agreements with results from microscopic images.
Experimental Investigation on Influence of Inclination and Curved Surface of Ship Bottom in Air Lubrication Method
Authors: Kawakita Chiharu , Hamada Tatsuya 
Published: November 2019

Abstract
The air lubrication method, which mixes millimeter bubbles into the flow around the hull and reduces frictional resistance, is expected to have a large energy saving effect among a number of marine energy saving technologies. Concerning the frictional drag reduction effect using the air lubrication method, in this study, the frictional drag reduction effect was experimentally investigated for gas-liquid two phase flow considering the influence of inclination and curved surface of the ship bottom. Measurement of local shear stress and measurement of void fraction distribution near the wall surface were carried out and the correlation between local shear stress and local void fraction distribution was grasped.
Lab-Scale Wind Tunnel Experiment Test of Wind Turbine Blades for Performance Evaluation
Authors: Moon Jae Sang , Park Sung Soo , Yu Sung Ho , Kang Sangkyun , Lee Jang-Ho 
Published: November 2019

Abstract
This study evaluates the performance of a HAWT blade model using the lab-scale wind tunnel experiment. The small-scale wind turbine blade model has been designed based on the newly developed airfoil, KA2. A 3-blade rotor, based on the blade model, is tested using the digital wind tunnel. The performance is estimated by measuring the rotor-induced shaft torque. To estimate the performance properly, two different methods have been used depending on the blade rotation speed. Test results are compared with the theoretical estimation by BEM. This study provides the methodology to the performance test of wind turbine blades using lab-scale experiment. Moreover, results represent the applicability of the KA2 airfoil to wind turbine blades.
A Numerical Study on Flow Characteristics of Super Sonic Diffuser for the Position and Nose Cone Angles of Center Body
Authors: Lee Sunghun , Lee Myeongwon , Park Jin , Kim Hongjip 
Published: November 2019

Abstract
The center body diffuser is one of supersonic diffuser that can simulate high-altitude environment. There is center-body structure inside the diffuser, and a complex fluid flow is occurred inside the diffuser because of the interaction of the CB structure with gas exhausted from the nozzle outlet. In this study, starting point and flow characteristics of diffuser were investigated according to changing the CB nose cone angle and the length of distance between nozzle and CB structure. The differences of the supersonic flow were compared through each parameter of CB distance and CB nose angle. First changed parameter was length between nozzle and CB. According to the length of distance between nozzle and CB, axial momentum was developed and oblique shock wave moved front of CB from end of CB nose cone. Also, when CB position was located on a certain length, starting point of CBD decreased. Next change parameter was angle of CB nose cone. According to the angle raised, angle of oblique shock wave was raised and radial momentum of supersonic diffuser developed. But, according to radial momentum of supersonic flow over certain angle, the starting pressure of CBD increased. Because axial momentum which isolated vacuum chamber from atmospheric pressure. Through these CFD analysis results, it was shown that angle and length of distance between nozzle and CB influent performance of CBD.
Numerical and Experimental Study of Thermal Behavior of an Electric Fuse in Electric Vehicle Li-Ion Battery Packs
Authors: Pulugundla Gautam , Dubey Prahit 
Published: November 2019

Abstract
In this paper, we perform 3D CFD simulations to understand the thermal operation of a High Breaking Capacity (H.B.C.) electric fuse within a Li-ion battery pack. The main focus is on evaluating the thermal behavior of a commercially available H.B.C. fuse containing four notched silver fuse elements through a numerical and experimental study that investigates the effect of the magnitude of electric current. For the numerical analysis we perform time-accurate, conjugate heat transfer-based 3D CFD simulations on high spatial resolution grids with commercial CFD software STAR-CCM+. Specifically, we utilize an electrodynamic potential model to calculate current density and the corresponding Ohmic heat generation of the fuse. The results of the numerical simulations with temperature dependent fuse material properties are validated against the experimental temperature measurements. The spatial distribution of temperature, and current in the fuse and its connected components are also compared for various input current values to evaluate the thermal performance of the fuse under a range of operating conditions.
A Numerical Study of Turbulence Model and Rebound Model Effect on Erosion Simulations in an Electrical Submersible Pump (ESP)
Authors: Zhu Haiwen , Zhang Jun , Zhu Jianjun , Rutter Risa , Zhang Hong-Quan 
Published: November 2019

Abstract
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.
Reconstruction of RANS Model and Cross-Validation of Flow Field Based on Tensor Basis Neural Network
Authors: Song Xudong , Zhang Zhen , Wang Yiwei , Ye Shuran , Huang Chenguang 
Published: November 2019

Abstract
The solution of the Reynolds-averaged Navier-Stokes (RANS) equation has been widely used in engineering problems. However, this model does not provide satisfactory prediction accuracy. Because the widely used eddy viscosity model assumes a linear relationship between the Reynolds stress and the average strain rate tensor and these linear models cannot capture the anisotropic characteristics of the actual flow. In this paper, two kinds of flow field structures of two-dimensional cylindrical flow and circular tube jet are calculated by using the RANS model. Secondly, in order to improve the prediction accuracy of the RANS model, the Reynolds stress of the RANS model is reconstructed by the tensor basis neural network algorithm based on nonlinear eddy viscosity model. Finally, the model trained by neural network is cross-validated, and compare the cross-test results with the traditional RANS k-eps model. The results show that the multi-layer neural network method has achieved good results in turbulence model reconstruction.