Research on Drag Reduction Performance of Bionic Shark Gill Jet Surface

2014 ◽  
Vol 654 ◽  
pp. 57-60 ◽  
Author(s):  
Zhao Gang ◽  
Fang Li ◽  
Wei Xin Liu ◽  
Ming Ming Liu ◽  
Hong Shi Bi
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Drag Reduction ◽  
Fluid Velocity ◽  
Reduction Rate ◽  
Frictional Resistance ◽  
Normal Velocity ◽  
Main Field ◽  
Maximum Drag Reduction ◽  
Pressure Resistance

According to the problem of bionic shark gill jet can reduce friction on shark surface, a model of bionic jet surface was established based on shark surface was analyzed by measurements, and its numerical simulation was processed by using RNG k-ε turbulence model. The results show that: the gill jet can reduce frictional resistance on shark surface, and the best drag reduction can be got when the speed of main field is 5m/s, furthermore the maximum drag reduction rate can be up to 17.15%. The pressure of jet hole upstream is reduced which due to the barrier to the facing fluid by the jet, so that the pressure resistance of jet surface is reduced as well. Besides, jet fluid is blocked in the boundary layer by mainstream fluid, which caused the fluid velocity of jet hole downstream is reduced, the thickness of boundary layer is increased, and the normal velocity gradient of wall is reduced, so as to achieve the effect of drag reduction.

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.

Direct numerical simulation of spatially developing turbulent boundary layers with uniform blowing or suction

2011 ◽  
Vol 681 ◽  
pp. 154-172 ◽  
Author(s):  
YUKINORI KAMETANI ◽  
KOJI FUKAGATA
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Drag Reduction ◽  
Skin Friction ◽  
Reduction Factor ◽  
Stream Velocity ◽  
Normal Velocity ◽  
Friction Drag ◽  
Local Skin

Direct numerical simulation (DNS) of spatially developing turbulent boundary layer with uniform blowing (UB) or uniform suction (US) is performed aiming at skin friction drag reduction. The Reynolds number based on the free stream velocity and the 99% boundary layer thickness at the inlet is set to be 3000. A constant wall-normal velocity is applied on the wall in the range, −0.01U∞ ≤ Vctr ≤ 0.01U∞. The DNS results show that UB reduces the skin friction drag, while US increases it. The turbulent fluctuations exhibit the opposite trend: UB enhances the turbulence, while US suppresses it. Dynamical decomposition of the local skin friction coefficient cf using the identity equation (FIK identity) (Fukagata, Iwamoto & Kasagi, Phys. Fluids, vol. 14, 2002, pp. L73–L76) reveals that the mean convection term in UB case works as a strong drag reduction factor, while that in US case works as a strong drag augmentation factor: in both cases, the contribution of mean convection on the friction drag overwhelms the turbulent contribution. It is also found that the control efficiency of UB is much higher than that of the advanced active control methods proposed for channel flows.

scholarly journals Investigation on drag reduction performance of pipeline with bioinspired microgrooved surface

2019 ◽  
Author(s):  
Weili Liu ◽  
Hongjian Ni ◽  
Peng Wang ◽  
Yi Zhou
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Pressure Loss ◽  
Fluid Transport ◽  
Fluid Dynamic ◽  
Reduction Rate ◽  
Orthogonal Analysis ◽  
Maximum Drag Reduction ◽  
Reduction Effect ◽  
Microgrooved Surface

Novel surface morphology of pipeline with transverse microgrooves was proposed for reducing the pressure loss of fluid transport. Numerical simulation and experimental research efforts were undertaken to evaluate the drag reduction performance of bionic pipeline. The computational fluid dynamic calculation, using SST κ-ω turbulent model, shown that the “vortex cushioning effect” and “driving effect” produced by the vortexes in the microgrooves were the main reason for the drag reduction. The shear stress of the microgrooved surface was reduced significantly owing to the decline of the velocity gradient; then bionic pipeline achieved drag reduction effect in the pipe and concentric annulus flow. The primary and secondary order of effect on the drag reduction and optimal microgroove geometric parameters were obtained by orthogonal analysis method. The comparative experiments were conducted in a water tunnel, and a maximum drag reduction rate of 3.21% was achieved. The numerical simulation and experimental results were cross-checked and consistent with each other to verify that the utilization of bionic theory to reduce the pressure loss of fluid transport is feasible. Results can provide theoretical guidance for the energy saving of pipeline transportation.

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 Global effect of local skin friction drag reduction in spatially developing turbulent boundary layer

2016 ◽  
Vol 805 ◽  
pp. 303-321 ◽  
Author(s):  
A. Stroh ◽  
Y. Hasegawa ◽  
P. Schlatter ◽  
B. Frohnapfel
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Control Region ◽  
Reduction Rate ◽  
Wall Turbulence ◽  
Local Skin ◽  
Control Schemes ◽  
Local Skin Friction ◽  
Friction Drag Reduction

A numerical investigation of two locally applied drag-reducing control schemes is carried out in the configuration of a spatially developing turbulent boundary layer (TBL). One control is designed to damp near-wall turbulence and the other induces constant mass flux in the wall-normal direction. Both control schemes yield similar local drag reduction rates within the control region. However, the flow development downstream of the control significantly differs: persistent drag reduction is found for the uniform blowing case, whereas drag increase is found for the turbulence damping case. In order to account for this difference, the formulation of a global drag reduction rate is suggested. It represents the reduction of the streamwise force exerted by the fluid on a plate of finite length. Furthermore, it is shown that the far-downstream development of the TBL after the control region can be described by a single quantity, namely a streamwise shift of the uncontrolled boundary layer, i.e. a changed virtual origin. Based on this result, a simple model is developed that allows the local drag reduction rate to be related to the global one without the need to conduct expensive simulations or measurements far downstream of the control region.

A Model for Velocity Profile in Turbulent Boundary Layer with Drag Reducing Surfactants

2005 ◽  
Vol 15 (3) ◽  
pp. 152-159 ◽  
Author(s):  
A. Krope ◽  
J. Krope ◽  
L.C. Lipus
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
General Problem ◽  
Frictional Resistance ◽  
Mixing Length ◽  
Mean Velocity ◽  
Pipe Section ◽  
Turbulent Water

Abstract A new model for mean velocity profile of turbulent water flow with added drag-reducing surfactants is presented in this paper. The general problem of drag due to frictional resistance is reviewed and drag reduction by the addition of polymers or surfactants is introduced. The model bases on modified Prandtl's mixing length hypothesis and includes three parameters, which depend on additives and can be evaluated by numerical simulation from experimental datasets. The advantage of the model in comparison with previously reported models is that it gives uniform curve for whole pipe section and can be determined for a new surfactant with less necessary measurements. The use of the model is demonstrated for surfactant Habon-G as an example.

Effect of Bionic Concave Surface to the Drag Reduction Performance of Cylinder Sealing Ring

2014 ◽  
Vol 1055 ◽  
pp. 152-156 ◽  
Author(s):  
Gang Zhao ◽  
Fang Li ◽  
Wei Xin Liu ◽  
Jian Ying Zhao ◽  
Hong Shi Bi
Keyword(s):  
Drag Reduction ◽  
Reduction Rate ◽  
Cylinder Block ◽  
Lubricating Oil ◽  
Concave Surface ◽  
Movement Speed ◽  
Piston Velocity ◽  
Friction Resistance ◽  
Sealing Ring ◽  
Maximum Drag Reduction

According to the problem of large friction resistance exists between the sealing ring and the cylinder block when the piston cylinder works, the drag reduction technology of bionic concave surface was applied in the sealing ring. By building a drag reduction motion model of sealing ring with concave surface of triangular arrangement, the effect of drag reduction performance decided by concave diameter and piston velocity was studied with the method of numerical simulation. The results show that: when the piston velocity is fixed, the maximum drag reduction rate can be achieved with the concave diameter is 1.5mm, and the maximum drag reduction rate is 15.72%. Meanwhile when the diameter of the concave is fixed, the drag reduction rate increased gradually with the increase of initial speed, the drag reducing effect is best at the speed of 0.6m/s. In the process of piston movement, lubricating oil in concave shakes, and makes the lubricating oil flow to the inside wall of cylinder, which play the role of lubrication, so as to achieve the effect of reducing friction and increasing the movement speed of piston.

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.

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