scholarly journals Effect of panel shape on hydrodynamic performances of vertical v-shaped double- slotted cambered otter-board

2018 ◽  
Vol 38 ◽  
pp. 03050 ◽  
Author(s):  
Lei Wang ◽  
Xun Zhang ◽  
Lu Min Wang ◽  
Hong Liang Huang ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Reference Data ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Moment Coefficient ◽  
Isosceles Trapezoid ◽  
Pitch Moment ◽  
Engineering Models ◽  
The Stability

The effect of panel shape on hydrodynamic performances of a vertical v-shaped double-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Three different shape panels (rhomboid, left trapezoid and isosceles trapezoid) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the three otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with the isosceles trapezoid shape panels was highest (2.103 at α=45°). The maximum Cy/Cx of the otter-board with the rhomboid shape panels was highest (3.976 at α=15°). A comparative analysis of Cm and Cp showed that the stability of otter-board model with the isosceles trapezoid shape panels is better in pitch, and the stability of otter-board model with the left trapezoid shape panels is better in roll. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

scholarly journals Effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board

2018 ◽  
Vol 38 ◽  
pp. 03049
Author(s):  
Lei WANG ◽  
Lu Min Wang ◽  
Jian Gao Shi ◽  
Wen Wen Yu ◽  
Guang Rui Qi ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Wind Speed ◽  
Reference Data ◽  
Center Of Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Engineering Models ◽  
The Stability

The effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Four different curvature (0.06,0.09, 0.12 and 0.15) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the four otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with the curvature (0.06) of two deflectors was highest (2.020 at °=55°). The maximum Cy/Cx of the otter-board with the curvature (0.12) of two deflectors was highest (3.655 at °=22.5°). A comparative analysis of Cm and Cp showed that the stability of otter-board model with the curvature (0.12) of two deflectors is better in pitch, and the stability of otter-board model with the curvature (0.06) of two deflectors is better in roll. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

scholarly journals Study of board bending degree on hydrodynamic performances of a single-layer cambered otter-board

2019 ◽  
Vol 131 ◽  
pp. 01120
Author(s):  
Lei Wang ◽  
Lu Min Wang ◽  
Yong Li Liu ◽  
Wen Wen Yu ◽  
Guang Rui Qi ◽  
...  
Keyword(s):  
Center Of Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Single Layer ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Engineering Models ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The effect of board bending degree on hydrodynamic performances of a single-layer cambered otter-board was investigated using engineering models in a wind tunnel. Three different bending degree boards were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the three otter-board models. Results showed that the bending of the board(No. 2, No. 3) increased the water resistance of the otter-board, and improved the lift coefficient of the otter-board in the small angle of attack (0°<α≤20 °) ; the maximum lift coefficients Cy of otter-board model (No. 1) was higher (1.680, α = 25°). the maximum lift–drag ratios of models (No. 1, No. 2 and No. 3) are 6.822 (α = 7.5 °), 6.533 (α = 2.5 °) and 6.384 (α = 5.0°), which showed that the board bending reduces the lift-to-drag ratio of the otter-board.The stability of the No. 3 model was better than those two models (No. 1, No. 2) in most range of attack angle, but No. 1 otter-board model had a better stability in roll of otter-board. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

Numerical Simulation of the Three Component Coefficients of Bridge

2012 ◽  
Vol 430-432 ◽  
pp. 2004-2007
Author(s):  
Yi Feng Huang ◽  
Ji Xin Yang
Keyword(s):  
Numerical Simulation ◽  
Wind Speed ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Moment Coefficient ◽  
Pitch Moment ◽  
Airflow Field ◽  
Bridge Girder

Numerical simulation has been carried out on the airflow field of bridge girder at construction state and completed bridge state under different wind speed and different wind angle of attack. The k-ε two-equation turbulence model is used in the numerical simulation by FLUENT. Variation of the three component coefficients can be obtained. The results show that drag coefficient and lift coefficient gradually becomes smaller and tends to stabilize, while pitch moment coefficient shows the trend of first increased and then reduced as wind speed increases. Drag coefficient and pitch moment coefficient does not change much and lift coefficient gradually becomes smaller with the change of wind angle of attack.

CFD Numerical Simulation of the Submarine Pipeline With Spoiler

2008 ◽  
Author(s):  
Jianping Zhao ◽  
Xuechao Wang
Keyword(s):  
Shear Stress ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Hangzhou Bay ◽  
Submarine Pipeline ◽  
Long Distance ◽  
Oil Transportation ◽  
Pipeline Failure ◽  
The Stability ◽  
Coating Weight

Submarine pipeline is one of the most important oil transportation components, pipeline failure due to over-span is the most serious failure mechanism. There are four reasons of pipeline span formation, including erosion of seabed, bumpy seabed, submarine pipeline climbing slope, and pipeline ascending to offshore platform. The Hangzhou Bay submarine pipeline is the most important subproject of the Yong-Hu-Ning network, and it is also the biggest long-distance pipeline for crude oil in China. Due to the dynamic nature of Hangzhou Bay, including high tides and high current amplified by the shallow waters, a self-burial method was selected as the best solution. By increasing the velocity of the stream between the pipeline and the seabed, shear stress on the seabed was enhanced. This localized increase in shear stress causes the seabed under the pipe to erode more quickly and facilitates self-burial of the pipe. To facilitate self-burial, a non-metallic vertical fin is fastened to the top of the pipeline. In this paper flow around a pipeline with and without a spoiler near a smooth wall is simulated with FLUENT version 6.1. The influences of the spoiler on pressure coefficient, lift coefficient, shear stress on the wall, as well as velocity profile are investigated. It is indicated that the coefficients for Drag and Inertia are increased with the application of the spoiler. The lift coefficient is reversed with the application of the spoiler increases the stability of the pipeline resulting in the reduction of the required coating weight.

scholarly journals Stabilometric assessment of vestibular function in children with a medium otitis

2021 ◽  
pp. 32-40
Author(s):  
Iuliia Lozova ◽  
Grigoriy Garyuk ◽  
Iryna Redka ◽  
Tatiana Pochuеva
Keyword(s):  
Comparative Analysis ◽  
Otitis Media ◽  
Center Of Pressure ◽  
Vestibular Function ◽  
Preschool Age ◽  
Balance Function ◽  
Suppurative Otitis Media ◽  
Eyes Closed ◽  
The Stability

Otitis media is one of the most common infectious diseases of the middle ear in preschool age, but its relationship with vestibular dysfunction remains controversial. The aim of the study was to carry out a comparative analysis of stabilometric indicators of preschool children with suppurative and non-suppurative otitis media. Materials and methods: 22 children with suppurative otitis media and 22 children with non-suppurative otitis media at the age from 4 to 7 years were examined by the method of static stabilometry on the device “MPFI Stabilograph 1” (LLC "ASTER IT", Kharkov, Ukraine). We took into account the indices of variation and distribution of the center of pressure, spectral and correlation indices of the stabilogram, as well as integral indices of stability (length, velocity and angle of postural oscillations) and the quality of the balance function in two sensory states (open and closed eyes), which were calculated in the software providing StabiliS. Results. In children with non-suppurative otitis media, the coordinates of the center-of-pressure corresponded (7.04 [2.16–10.09]; -1.14 [-28.90–9.11]), and with suppurative otitis media – (7.04 [3.30–16.16]; -13.72 [(-25.17)–(-10.30)]) with closed eyes. The averaged figure of the projection of the center-of-pressure in the test with eyes closed is actually represented by a circle in both groups, but with open eyes it is represented by an ellipse, which, in case of non-suppurative otitis media, is stretched along the sagittal axis, and in case of suppurative otitis media, along the frontal axis. In both sensory states, children with non-suppurative otitis media were characterized by large (p≤0.05) values of KurtosisX, Length and lower (p≤0.05) values of CC0X, Pup2Sigma compared with non-purulent otitis media. Conclusions: In preschool age, suppurative otitis media more significantly disrupts the balance function compared with non-suppurative otitis media, which was manifested by a significant decrease in the stability of the main stance and the predictability of oscillatory movements compared with non-suppurative otitis media

scholarly journals Analisis Airfoil Double-Slot Flap LS(01)-0417 MOD Dengan Airfoil Tanpa Flap Nasa SC(2) 0610

2018 ◽  
Vol 11 (2) ◽  
pp. 49
Author(s):  
Gaguk Jatisukamto ◽  
Mirna Sari
Keyword(s):  
Computational Fluid Dynamic ◽  
Static Pressure ◽  
Fluid Dynamic ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Airflow Velocity ◽  
The Difference ◽  
The Stability

Kestabilan pesawat terbang ditentukan oleh desain airfoil sayap dan ekor. Perbedaan kecepatan aliran udara antara permukaan atas dan bawah airfoil menghasilkan perbedaan tekanan sehingga akan memberikan gaya angkat (lift) pada sayap. Perbedaan tekanan udara pada permukaan sayap dinyatakan dengan pressure coefficient (Cp), yaitu perbedaan tekanan statik lokal dengan tekanan statik aliran bebas. Koefisien lift (Cl) adalah rasio antara gaya angkat (lift) dengan tekanan dinamis. Peningkatan angka CL sebesar 20,4% pada riset sebelumnya diperoleh berdasarkan simulasi penambahan flap. Tujuan penelitian ini adalah membandingkan hasil simulasi airfoil double slot flap LS(01)-0417 MOD  dengan airfoil NASA SC(2) 0610 yang tanpa flap dan mencari korelasi antara sudut serang (?) dengan koefisien lift (Cl ).Metodologi penelitian dilakukan dengan simulasi Computational Fluid Dynamic (CFD). Hasil penelitian dapat disimpulkan bahwa koefisien lift CL untuk airfoil double slot flap LS(01)-0417 MOD menghasilkan CL = 1,498 sedangkan dengan sudut serang ? = 16o sedangkan airfoil NASA SC(2) 0610 tanpa flap memiliki nilai CL = 1,095 dengan sudut serang 13o. The stability of the aircraft is ordered by the airfoil design of the wings and the tail. The difference in flow velocity between the surface and the bottom of the airfoil will produce styles that will present lift  on the wings. The difference in airflow velocity between the top and bottom surfaces of the airfoil produces a pressure difference so it will provide lift (lift) on the wing. The lift coefficient (CL) is the ratio between lift with dynamic pressure. The difference of air pressure on the wing surface is expressed by pressure coefficient (Cp), the difference of local static pressure with free flow static pressure. The lift coefficient (Cl) is the ratio of lift to dynamic pressure. An increase in CL value of 20.4% in previous research was obtained based on the simulation of flap addition. The purpose of this research is comparison between airfoil double slot flap LS (01)-0417 MOD with airfoil NASA SC (2) 0610 without flap and search between angle of attack (?) with coefficient of lift (Cl). Method research is done by Computational Fluid Dynamic (CFD). The result of this research can be concluded that lift coefficient CL for double slot airfoil flap LS (01)-0417 MOD yield CL = 1,498 while with angle of attack ? = 16o while airfoil NASA SC (2) 0610 without flap have value CL = 1,095 with angle of attack 13o

scholarly journals Unsteady Simulation of Transonic Buffet of a Supercritical Airfoil with Shock Control Bump

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 203
Author(s):  
Yufei Zhang ◽  
Pu Yang ◽  
Runze Li ◽  
Haixin Chen
Keyword(s):  
Lift Coefficient ◽  
Pressure Coefficient ◽  
Flow Characteristics ◽  
Control Effect ◽  
Shock Control Bump ◽  
Shock Control ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Unsteady Simulation ◽  
Drag Ratio

The unsteady flow characteristics of a supercritical OAT15A airfoil with a shock control bump were numerically studied by a wall-modeled large eddy simulation. The numerical method was first validated by the buffet and nonbuffet cases of the baseline OAT15A airfoil. Both the pressure coefficient and velocity fluctuation coincided well with the experimental data. Then, four different shock control bumps were numerically tested. A bump of height h/c = 0.008 and location xB/c = 0.55 demonstrated a good buffet control effect. The lift-to-drag ratio of the buffet case was increased by 5.9%, and the root mean square of the lift coefficient fluctuation was decreased by 67.6%. Detailed time-averaged flow quantities and instantaneous flow fields were analyzed to demonstrate the flow phenomenon of the shock control bumps. The results demonstrate that an appropriate “λ” shockwave pattern caused by the bump is important for the flow control effect.

Experimentally Determined Stability Parameters of a Subsonic Cascade Oscillating Near Stall

1978 ◽  
Vol 100 (1) ◽  
pp. 111-120 ◽  
Author(s):  
F. O. Carta ◽  
A. O. St. Hilaire
Keyword(s):  
Phase Angle ◽  
Incidence Angle ◽  
Minor Effect ◽  
Significant Finding ◽  
Force Coefficient ◽  
Stability Parameters ◽  
Free System ◽  
Pressure Transducers ◽  
Moment Coefficient ◽  
The Stability

Tests were performed on a linear cascade of airfoils oscillating in pitch about their midchords at frequencies up to 17 cps, at free-stream velocities up to 200 ft/s, and at interblade phase angles of 0 deg and 45 deg, under conditions of high aerodynamic loading. The measured data included unsteady time histories from chordwise pressure transducers and from chordwise hot films. Unsteady normal force coefficient, moment coefficient, and aerodynamic work per cycle of oscillation were obtained from integrals of the pressure data, and indications of the nature and extent of the separation phenomenon were obtained from an analysis of the hot-film response data. The most significant finding of this investigation is that a change in interblade phase angle from 0 deg to 45 deg radically alters the character of the unsteady blade loading (which governs its motion in a free system) from stable to unstable. Furthermore, the stability or instability is governed primarily by the phase angle of the pressure distribution (relative to the blade motion) over the forward 10–15 percent of the blade chord. Reduced frequency and mean incidence angle changes were found to have a relatively minor effect on stability for the range of parameters tested.

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