Influence of Jet Hole Configuration on Drag Reduction of Bionic Jet Surface

2013 ◽  
Vol 461 ◽  
pp. 725-730 ◽  
Author(s):  
Yun Qing Gu ◽  
Jing Ru ◽  
Zhao Gang ◽  
Zhao Yuan Li ◽  
Wen Bo Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Reduction Rate ◽  
Experimental Tests ◽  
Isosceles Triangle ◽  
Hole Configuration ◽  
Field Velocity ◽  
Jet Velocity ◽  
Reduction Characteristics

According to the jet hole configuration mode of bionic jet surface and its influence on the drag reduction, as the basic form of jet hole configuration is the isosceles triangle elements, so this was used to establish the computational model of jet hole configuration. In this case, the height and base of the triangles were considered as variable. The SST k-ω turbulence model was used to simulate and research the drag reduction characteristics of bionic jet surface in different configuration modes of jet holes at the main flow field velocity value of 20m/s and the jet velocity value of 0.4~2.0m/s. Also the influence of different configurations of height and base on drag reduction characteristics of bionic jet surface was studied, which got the optimum size of jet hole configuration. Results show that in triangle configuration elements, the drag reduction characteristics of bionic jet surface can be influenced by the jet hole of different configurations of height and base; the drag reduction of bionic jet surface reaches the peak of 32.74% at 8mm height, 11mm base, and the jet velocity value of 2.0m/s. At the same flow field velocity, the drag reduction rate results achieved by experimental tests and by numerical simulation were changing consistently and were found same, which verifies correctness of numerical simulation results.

scholarly journals Study on the Drag Reduction Characteristics of the Surface Morphology of Paramisgurnus dabryanus Loach

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1357
Author(s):  
Liyan Wu ◽  
Jiaqi Wang ◽  
Guihang Luo ◽  
Siqi Wang ◽  
Jianwei Qu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Drag Reduction ◽  
Reduction Rate ◽  
Underwater Vehicles ◽  
Flow Channel ◽  
Numerical Control ◽  
Reduction Mechanism ◽  
Paramisgurnus Dabryanus ◽  
Reduction Characteristics

The drag reduction design of underwater vehicles is of great significance to saving energy and enhancing speed. In this paper, the drag reduction characteristics of Paramisgurnus dabryanus loach was explored using 3D ultra-depth field microscopy to observe the arrangement of the scales. Then, a geometric model was established and parameterized. A simulated sample was processed by computer numerical control (CNC) machining and tested through using a flow channel bench. The pressure drop data were collected by sensors, and the drag reduction rate was consequently calculated. The test results showed that the drag reduction rate of a single sample could reach 23% at a speed of 1.683 m/s. Finally, the experimental results were verified by numerical simulation and the drag reduction mechanism was explored. The boundary layer theory and RNG k-ε turbulence model were adopted to analyze the velocity contour, pressure contour and shear force contour diagrams. The numerical simulation results showed that a drag reduction effect could be achieved by simulating the microstructure of scales of the Paramisgurnus dabryanus loach, showing that the results are consistent with the flow channel experiment and can reveal the drag reduction mechanism. The bionic surface can increase the thickness of boundary layer, reduce the Reynolds number and wall resistance. The scales disposition of Paramisgurnus dabryanus loach can effectively reduce the surface friction, providing a reference for future research on drag reduction of underwater vehicles such as ships and submarines.

scholarly journals An investigation on the drag reduction performance of bioinspired pipeline surfaces with transverse microgrooves

2020 ◽  
Vol 11 ◽  
pp. 24-40 ◽  
Author(s):  
Weili Liu ◽  
Hongjian Ni ◽  
Peng Wang ◽  
Yi Zhou
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Pressure Loss ◽  
Fluid Transport ◽  
Reduction Rate ◽  
Orthogonal Analysis ◽  
Maximum Drag Reduction ◽  
Reduction Effect ◽  
Save Energy ◽  
Microgrooved Surface

A novel surface morphology for pipelines using transverse microgrooves was proposed in order to reduce the pressure loss of fluid transport. Numerical simulation and experimental research efforts were undertaken to evaluate the drag reduction performance of these bionic pipelines. It was found that the vortex ‘cushioning’ and ‘driving’ effects produced by the vortexes in the microgrooves were the main reason for obtaining a drag reduction effect. The shear stress of the microgrooved surface was reduced significantly owing to the decline of the velocity gradient. Altogether, bionic pipelines achieved drag reduction effects both in a pipeline and in a concentric annulus flow model. The primary and secondary order of effect on the drag reduction and optimal microgroove geometric parameters were obtained by an orthogonal analysis method. The comparative experiments were conducted in a water tunnel, and a maximum drag reduction rate of 3.21% could be achieved. The numerical simulation and experimental results were cross-checked and found to be consistent with each other, allowing to verify that the utilization of bionic theory to reduce the pressure loss of fluid transport is feasible. These results can provide theoretical guidance to save energy in pipeline transportations.

Simulation and Analysis of Flow Field Control in Bionic Jet Surface for Drag Reduction

2013 ◽  
Vol 461 ◽  
pp. 746-750
Author(s):  
Zhao Gang ◽  
Fang Li ◽  
Jun Wei Du ◽  
Muhammad Farid ◽  
Dong Yang Zang
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Drag Reduction ◽  
Velocity Gradient ◽  
Reverse Flow ◽  
Reduction Rate ◽  
Frictional Resistance ◽  
Longitudinal Direction ◽  
Bottom Layer ◽  
Control Behavior

Numerical simulation was used with SST turbulence model on the drag reduction characteristics of bionic jet surface, which clarified the reason that the bionic jet surface could reduce the frictional resistance and the control behavior to the flow field near the wall. Results show that when the area of the jet hole is constant, the higher the ratio of the length along the longitudinal direction of jet hole and that of jet surface is, the better the drag reduction effect is. With the jet speed and jet flux increasing, the drag reduction rate will increase gradually until the maximum of 35.97%. The frictional resistance of bionic jet surface will decrease by increasing the area of reverse flow and decreasing the velocity gradient of the wall; the control behavior of jet surface to boundary layer embodies the shear stress in the bottom of boundary layer caused by the reverse flow in the back flow surface is opposite to the main flow field direction when the shear flow near the wall converges the jet impedance, which causes the low speed reverse rotating vortex pair in the downstream of jet hole, the secondary vortex near the wall caused by the extent of reverse vortex towards the downstream can increase the boundary bottom layer thickness and decrease the velocity gradient and frictional resistance.

scholarly journals Direct Numerical Simulation of Flow around a Circular Cylinder Controlled Using Plasma Actuators

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Taichi Igarashi ◽  
Hiroshi Naito ◽  
Koji Fukagata
Keyword(s):  
Numerical Simulation ◽  
Circular Cylinder ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Three Dimensional ◽  
Reduction Rate ◽  
Plasma Actuators ◽  
Two Dimensional ◽  
Freestream Velocity ◽  
The Mean

Flow around a circular cylinder controlled using plasma actuators is investigated by means of direct numerical simulation (DNS). The Reynolds number based on the freestream velocity and the cylinder diameter is set atReD=1000. The plasma actuators are placed at±90° from the front stagnation point. Two types of forcing, that is, two-dimensional forcing and three-dimensional forcing, are examined and the effects of the forcing amplitude and the arrangement of plasma actuators are studied. The simulation results suggest that the two-dimensional forcing is primarily effective in drag reduction. When the forcing amplitude is higher, the mean drag and the lift fluctuations are suppressed more significantly. In contrast, the three-dimensional forcing is found to be quite effective in reduction of the lift fluctuations too. This is mainly due to a desynchronization of vortex shedding. Although the drag reduction rate of the three-dimensional forcing is slightly lower than that of the two-dimensional forcing, considering the power required for the forcing, the three-dimensional forcing is about twice more efficient.

scholarly journals Experimental Study on Drag Reduction Characteristics of Bionic Earthworm Self-Lubrication Surface

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Guomin Liu ◽  
Xueqiao Wu ◽  
Meng Zou ◽  
Yuying Yan ◽  
Jianqiao Li
Keyword(s):  
Drag Reduction ◽  
Flow Rate ◽  
Experimental Testing ◽  
Reduction Rate ◽  
Normal Pressure ◽  
Secondary Effects ◽  
Quadratic Regression ◽  
Regression Test ◽  
Reduction Effect ◽  
Reduction Characteristics

In the present study, a coupling bionic method is used to study the drag reduction characteristics of corrugated surface with lubrication. In order to test the drag reduction features, bionic specimen was prepared inspired by earthworm surface and lubrication. Based on the reverse engineering method, nonsmooth curve of earthworm surface was extracted and the bionic corrugated sample was designed, and the position of lubrication hole was established by experimental testing. The lubricating drag reduction performance, the influence of normal pressure, the forward velocity, and the flow rate of lubricating fluid on the forward resistance of the bionic specimens were analyzed through a single factor test by using the self-developed test equipment. The model between the forward resistance and the three factors was established through the ternary quadratic regression test. The results show that the drag reduction effect is obvious, the drag reduction rate is 22.65% to 34.89%, and the forward resistance decreases with the increase of the forward velocity, increases with the increase of the normal pressure, and decreases first and then becomes stable with the increase of flow rate of lubricating fluid. There are secondary effects on forward resistance by the three factors, and the influencing order is as follows: normal pressure>flow rate of lubricating fluid>forward velocity.

Effect of Jet Hole Size on Drag Reduction Performance of Bionic Jet Surface

2014 ◽  
Vol 1022 ◽  
pp. 87-90
Author(s):  
Zhao Gang ◽  
Fang Li ◽  
Wei Xin Liu ◽  
Shu Zhang ◽  
Hong Shi Bi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
High Speed ◽  
Reduction Rate ◽  
Surface Model ◽  
Surface Boundary ◽  
Hole Size ◽  
Friction Resistance ◽  
Rectangular Jet ◽  
Flow Length

According to the problem of drag reduction on bionic jet surface, a rectangular jet surface model which is similar to shark branchial shape was built, and numerical simulation was processed by using SST k-ω turbulence model, moreover, influence of jet hole size on the drag reduction performance of jet surface was studied. The results show that: the effect of flow length of rectangular jet hole on the drag reduction is remarkable, with the increase of flow length, fluid friction resistance of the jet surface decreases, the maximum drag reduction rate was 14.38%, and the results of numerical simulation was verified by carrying out experiments. The jet fluid decreases the sweep on the wall of mainstream high speed fluid, which increases the thickness of jet surface boundary layer, thereby reducing the surface friction of the jet hole downstream.

Study of Truck’s Aerodynamic Drag Reduction Based on Jet

2014 ◽  
Vol 635-637 ◽  
pp. 316-319
Author(s):  
Peng Guo ◽  
Jun Yuan Zhang ◽  
Qi Fei Li ◽  
Xing Jun Hu
Keyword(s):  
Numerical Simulation ◽  
Comparative Analysis ◽  
Flow Field ◽  
Drag Reduction ◽  
Pressure Distribution ◽  
Aerodynamic Drag ◽  
Outer Flow ◽  
Air Movement ◽  
Maximum Drag Reduction ◽  
Aerodynamic Drag Reduction

Multiple schemes are adapted on truck's outer flow field based on numerical simulation. Comparative analysis with the state of air flow, the pressure distribution, the air movement between the cab and cargo is pursued, then obtain the effect of jet flow velocity to the truck Cd. With the increasing of the jet velocity, Cd increases first and then decreases. The maximum drag reduction can reaches 7.38%.

scholarly journals Drag reduction characteristics and flow field analysis of textured surface

Friction ◽  
2016 ◽  
Vol 4 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Qingshun Bai ◽  
Jinxuan Bai ◽  
Xiangpan Meng ◽  
Chengcheng Ji ◽  
Yingchun Liang
Keyword(s):  
Flow Field ◽  
Drag Reduction ◽  
Field Analysis ◽  
Textured Surface ◽  
Flow Field Analysis ◽  
Reduction Characteristics

Numerical Simulation of Micro Flow Field on Biomimetic Sharkskin Micro-Grooved Surface

2014 ◽  
Vol 884-885 ◽  
pp. 378-381 ◽  
Author(s):  
Yue Hao Luo ◽  
Yu Fei Liu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Drag Reduction ◽  
Reduction Mechanism ◽  
Urgent Problem ◽  
Grooved Surface ◽  
Micro Flow ◽  
Important Significance

It is well-known that sharkskin surface has the effect of inhibiting the occurrence of turbulence and reducing the wall resistance, however, the drag reduction mechanism has developed into an urgent problem to be resolved now. According to the actual circumstance, for purpose of obtaining the best drag-reducing efficiency, the biomimetic sharkskin micro-grooved surface is designed according to the relevant literatures and research achievements, and numerical simulation of the micro flow field on the biomimetic sharkskin surface is carried out comprehensivley, which has the important significance to explain the drag reduction mechanism.

Numerical and experimental investigation of damage effect on a hemispherical parachute performance

2018 ◽  
Vol 234 (5) ◽  
pp. 1050-1060
Author(s):  
Fakhri Etemadi ◽  
Mahmoud Mani ◽  
Ramin Kamali Moghadam
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Flow Behavior ◽  
Tensile Load ◽  
Experimental Tests ◽  
Open Circuit ◽  
Damage Effect ◽  
Pressure Distributions ◽  
Parachute Canopy ◽  
Comparison Of The Results

The effect of the canopy fabric damage on parachute performance has been investigated numerically and experimentally in the present paper. For this aim, first, flow structure around the parachute canopy has been studied for both damaged and undamaged parachutes. Then, the drag coefficient as the main characteristic of a parachute performance has been examined and compared experimentally and numerically in four Reynolds numbers. Experimental tests for undamaged and damaged canopies have been carried out in an open-circuit wind tunnel laboratory at the velocities 15, 20, 25, and 30 m/s. In order to measure the drag force, a valid tensile load-cell has been used. Also, the smoke flow visualization has been utilized to find the flow behavior at different regions of the parachute. For the numerical simulation, an incompressible pressure-based CFD code using the finite volume method has been applied to solve the complex turbulent flow field around the inflated parachute canopy. To increase accuracy of the numerical simulation, the permeability boundary condition on the parachute canopy has been implemented and its effects have been considered on the flow field. The numerical results indicate that the permeability assumption on the canopy makes desirable results compatible with the experimental ones. Moreover, comparison of the results between damaged and undamaged canopies demonstrates significant differences in the streamlines, pressure distributions, and drag coefficients. As the reliability is the main criterion for the parachute system, investigation on the damage effects would be useful and it has been considered in the present work.

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