scholarly journals Experimental and Numerical Study of Water Entry Supercavity Influenced by Turbulent Drag-Reducing Additives

2014 ◽  
Vol 6 ◽  
pp. 280643 ◽  
Author(s):  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
High Speed ◽  
Numerical Study ◽  
Ccd Camera ◽  
Water Entry ◽  
Multiphase Model ◽  
Turbulent Drag ◽  
Unsteady Rans ◽  
Simulation Results

The configurational and dynamic characteristics of water entry supercavities influenced by turbulent drag-reducing additives were studied through supercavitating projectile approach, experimentally and numerically. The projectile was projected vertically into water and aqueous solution of CTAC with weight concentrations of 100, 500, and 1000 ppm, respectively, using a pneumatic nail gun. The trajectories of the projectile and the supercavity configuration were recorded by a high-speed CCD camera. Besides, water entry supercavities in water and CTAC solution were numerically simulated based on unsteady RANS scheme, together with application of VOF multiphase model. The Cross viscosity model was adopted to represent the fluid property of CTAC solution. It was obtained that the numerical simulation results are in consistence with experimental data. Numerical and experimental results all show that the length and diameter of supercavity in drag-reducing solution are larger than those in water, and the drag coefficient is smaller than that in water; the maintaining time of supercavity is longer in solution as well. The surface tension plays an important role in maintaining the cavity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation and drag reduction.

scholarly journals Numerical Study of Natural Supercavitation Influenced by Rheological Properties of Turbulent Drag-Reducing Additives

2014 ◽  
Vol 6 ◽  
pp. 275316 ◽  
Author(s):  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Study ◽  
Cavitation Number ◽  
Navier Stokes ◽  
Multiphase Model ◽  
Turbulent Vortex ◽  
Turbulent Drag ◽  
Simulation Results ◽  
Overall Resistance

Natural supercavitations in water and turbulent drag-reducing solution were numerically simulated using unsteady Reynolds averaged Navier-Stokes (RANS) scheme with mixture-multiphase model. The Cross viscosity equation was adopted to represent the fluid property of aqueous solution of drag-reducing additives. The characteristics of natural supercavity configuration and overall resistance of the navigating body were presented, respectively. The numerical simulation results indicated that, at the same cavitation number, the length and diameter of supercavity in drag-reducing solution are larger than those in water, and the drag coefficient of navigating body in solution is smaller than that in water; the surface tension plays an important role in incepting and maintaining the cavity. Turbulent drag-reducing additives have the potential in enhancement of supercavitation, drag reduction, and decrease of turbulent vortex structures. Numerical simulation results are consistent with the available experimental data.

scholarly journals Numerical study of savonius water turbine performance by adding deflector to advancing blade side

2018 ◽  
Author(s):  
Priyo Agus Setiawan ◽  
Anda Iviana Juniani ◽  
Adi Wirawan Husodo
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Numerical Study ◽  
Renewable Energy Sources ◽  
Power Coefficient ◽  
Turbine Performance ◽  
Water Turbine ◽  
Unsteady Rans ◽  
Deflector Plate ◽  
Coarse To Fine

As one of the best renewable energy sources, hydropower becomes more predictable sourcecompared to wind energy and Savonius which its performance does not contingent to fluid flowdirection. In this present, computational Fluid Dynamics acomplished by Finite Volume Methodand unsteady RANS equation were applied to analyze the numerical simulation. The presentstudy investigated the performance of Savonius Turbine by adding deflector plate installed toadvancing blade side at 5, 10, 15, 30 and 45 of deflector angles in the direction of the fluid flow.The viscous turbulence model used realizable k-epsilon (RKE) and its descritization usedsecond order upwind. The type of mesh was made from coarse to fine meshing with 8 (eight)types of meshing and the grid independency of the numerical simulation had been validated bythe publish experimental data at TSR of 1,078. Grid independency occured at meshing G withthe error lower than 5 % compared to published experimental data. The result of this studyshows that the performance of Savonius turbine increased by adding deflector in advancingblade side with the maximum torque and power coefficient at 30 of deflector angle.

An Investigation of the Different Flow Regimes in a Rotating Drum through Experimental and Simulation

2014 ◽  
Vol 802 ◽  
pp. 215-219
Author(s):  
D.A. Santos ◽  
Irineu Petri Jr. ◽  
C.R. Duarte ◽  
M.A.S. Barrozo
Keyword(s):  
Experimental Data ◽  
Particle Velocity ◽  
High Speed ◽  
Video Camera ◽  
Particle Dynamic ◽  
Multiphase Model ◽  
Rotating Drum ◽  
High Speed Video Camera ◽  
Simulation Results ◽  
Good Agreement

This paper aims to investigate the particle dynamic behavior in a rotating drum operating in a rolling regime under different rotating velocity, based on experimental results and simulations. Simple superphosphate fertilizer (SSP) was used as particulate matter in the current study. The Eulerian–Eulerian multiphase model along with the kinetic theory of granular flow was used in the simulations. In order to evaluate the simulation results, velocity distributions of the particulate phase were compared with experimental data. The experimental particle velocity distribution was obtained by using a high speed video camera. The numerical simulation results showed significant insights towards understanding of the particle dynamic in a rotating drum. The simulated results of particle velocity were in good agreement with the experimental data.

scholarly journals Numerical Simulation on the Cavitation Flow of High Speed Oblique Water Entry of Revolution Body

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Qing Mu ◽  
Yipin Lv ◽  
Kangjian Wang ◽  
Tianhong Xiong ◽  
Wenjun Yi
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Water Entry ◽  
Hydrodynamic Characteristics ◽  
Multiphase Model ◽  
Cavitation Flow ◽  
Entry Angle ◽  
Positive Direction ◽  
Cavity Shape ◽  
The Revolution

To explore the effects of water entry angle on the cavitation flow field of high-speed revolution body, based on the finite volume method, VOF (Volume of Fluid) multiphase model, Schnerr-Sauer cavity model, SST k-ω turbulence model, and dynamic mesh method, numerical simulation for modeling the oblique water entry of revolution body at high speed is performed. The evolution laws of cavity shape, motion characteristics, and hydrodynamic characteristics of revolution body at different water entry angles are analyzed. The results show that the numerical calculation method can effectively simulate the change of cavity shape during the water entry of the revolution body. With the increase of water entry angle, the uplift of liquid level decreases in the positive direction of the open cavity and increases in the negative direction. The angle of water entry has little effect on the velocity of the revolution body. The larger the angle of water entry, the greater the peak pressure and the faster the pressure decay at the moment of water entry.

scholarly journals Development of Depth-Limited Wave Boundary Layers over a Smooth Bottom

2020 ◽  
Vol 9 (1) ◽  
pp. 27
Author(s):  
Hitoshi Tanaka ◽  
Nguyen Xuan Tinh ◽  
Xiping Yu ◽  
Guangwei Liu
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Boundary Layers ◽  
Wave Motion ◽  
Numerical Study ◽  
Experiment Data ◽  
Tidal Motion ◽  
Long Period ◽  
Simulation Results ◽  
Wave Boundary

A theoretical and numerical study is carried out to investigate the transformation of the wave boundary layer from non-depth-limited (wave-like boundary layer) to depth-limited one (current-like boundary layer) over a smooth bottom. A long period of wave motion is not sufficient to induce depth-limited properties, although it has simply been assumed in various situations under long waves, such as tsunami and tidal currents. Four criteria are obtained theoretically for recognizing the inception of the depth-limited condition under waves. To validate the theoretical criteria, numerical simulation results using a turbulence model as well as laboratory experiment data are employed. In addition, typical field situations induced by tidal motion and tsunami are discussed to show the usefulness of the proposed criteria.

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

Characteristics of Heat Transfer and Flow on a Surface With Small-Scale Concave Spherical Pits

2008 ◽  
Author(s):  
J. S. Wang ◽  
Y. Qiu ◽  
L. Y. Li
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Small Scale ◽  
Heat Transfer Mechanism ◽  
Transfer Enhancement ◽  
Special Effect ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag ◽  
Simulation Results ◽  
Turbulent Coherent Structure

Small-scale concave spherical pits, which have a special effect on heat transfer enhancement and turbulent drag reduction, are investigated by numerical simulation in detail. Two kinds of small-scale concave pits structures are designed on surface of a plate, which are located in the bottom of a rectangle channel. The characteristics of heat transfer and flow in channel are investigated and compared with a same channel with plate bottom by means of LES. Flow structure and temperature distribution near the pits are analyzed. The numerical simulation results indicate that the concave spherical pits disturb the flow field and vortex is induced by the pits. The turbulent coherent structure is affected by the induced vortex. The numerical simulation indicates that small scale pit can generate the vortex in couple. The range of vortex is accord with the array of small scale pit. The small scale pit can enhance the intensity of vortex. As a result, the temperature field near the pit is changed with generation of the vortex. The heat transfer mechanism on plate with small scale concave spherical pit is summarized.

Impact Simulation of a Crashworthy Composite Fuselage Section with Energy-Absorbing Floor

2014 ◽  
Vol 529 ◽  
pp. 102-107
Author(s):  
Hai Bo Luo ◽  
Ying Yan ◽  
Xiang Ji Meng ◽  
Tao Tao Zhang ◽  
Zu Dian Liang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Dynamic Response ◽  
Relative Error ◽  
High Strength ◽  
Computer Code ◽  
Impact Simulation ◽  
Average Acceleration ◽  
Simulation Results ◽  
Energy Absorbing

A 7.8m/s vertical drop simulate of a full composite fuselage section was conducted with energy-absorbing floor to evaluate the crashworthiness features of the fuselage section and to predict its dynamic response to dummies in future. The 1.52m diameter fuselage section consists of a high strength upper fuselage frame, one stiff structural floor and an energy-absorbing subfloor constructed of Rohacell foam blocks. The experimental data from literature [6] were analyzed and correlated with predictions from an impact simulation developed using the nonlinear explicit transient dynamic computer code MSC.Dytran. The simulated average acceleration did not exceed 13g, by contrast with experimental results, whose relative error is less than 11%. The numerical simulation results agree with experiments well.

scholarly journals Mechatronic Device for Locomotor Training

2016 ◽  
Vol 10 (4) ◽  
pp. 310-315 ◽  
Author(s):  
Sławomir Duda ◽  
Damian Gąsiorek ◽  
Grzegorz Gembalczyk ◽  
Sławomir Kciuk ◽  
Arkadiusz Mężyk
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Measurement Data ◽  
Healthy Person ◽  
Control Algorithms ◽  
Design Team ◽  
Locomotor Training ◽  
Interdisciplinary Design ◽  
Machine Control ◽  
Simulation Results

Abstract This paper presents a novel mechatronic device to support a gait reeducation process. The conceptual works were done by the interdisciplinary design team. This collaboration allowed to perform a device that would connect the current findings in the fields of biomechanics and mechatronics. In the first part of the article shown a construction of the device which is based on the structure of an overhead travelling crane. The rest of the article contains the issues related to machine control system. In the prototype, the control of drive system is conducted by means of two RT-DAC4/PCI real time cards connected with a signal conditioning interface. Authors present the developed control algorithms and optimization process of the controller settings values. The summary contains a comparison of some numerical simulation results and experimental data from the sensors mounted on the device. The measurement data were obtained during the gait of a healthy person.

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