scholarly journals Lift-to-Drag Ratio of the Application of Hydrofoil With Variation Mounted Position on High-Speed Patrol Vessel

CFD letters ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1-9
Author(s):  
Muhammad Arif Budiyanto ◽  
Naufal Yudha Prawira ◽  
Haekal Dwiputra
Keyword(s):  
High Speed ◽  
High Performance ◽  
Hydrodynamic Performance ◽  
Comparison Result ◽  
Academic Literature ◽  
Marine Vehicles ◽  
Basic Model ◽  
Optimum Position ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The hydrofoil is one of the hydrodynamic support technologies for marine vehicles that provide a high performance and are feasible to operate. The mounting position of hydrofoils on the hull is one of the keys to improving the hydrodynamic performance, where the existing academic literature to find the optimum position of hydrodynamic is still deficient. The objective of this study is to compare the mounting locations of hydrofoil in the horizontal axis in a high-speed patrol vessel. The comparison result is based on the computational fluid dynamics where the basic model was validated using experimental data. Three mounting location cases of hydrofoils were performed i.e. middle section, stern section, and behind the stern. The result shows that the optimal hydrofoil mounting position is after the transom. In this position, the value of the lift-to-drag ratio is higher by an average of 10% - 29% compared to other positions depending on the speed of the ship.

Based on Imitation Seagull Airfoil UVA Wing Numerical Simulation

2012 ◽  
Vol 271-272 ◽  
pp. 791-796
Author(s):  
Xin Hua ◽  
Wei Shao ◽  
Chun Hua Zhang ◽  
Zhi Qiang Zhang
Keyword(s):  
Numerical Simulation ◽  
High Performance ◽  
Lift Coefficient ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Wing Scale ◽  
Fluent Software ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Straight Wing

Wing aircraft is one of the major components to generate lift, in today's energy shortage, design the high lift-to-drag ratio wing is the goal pursued by, The author in the exploration of bionic airfoil aerodynamic characteristics on the basis of, which will be applied to straight wing design so as to improve the aerodynamic performance of aircraft.Our research mainly includes two aspects: first, the use of imitation seagull airfoil and NACA4412 airfoil are designed into the straight wing. The use of FLUENT software in Re=300000condition carries on the numerical simulation results show that the ratio of gull wing airfoil than NACA4412 lift coefficient increased by 13%, while the lift to drag ratio,is improved by 46.83%. Then, using the similarity principle, the wing scale, was tested in a wind tunnel test, the results obtained with the simulation are consistent. Airfoil design for the design of high performance wing opened a new way.

Numerical Investigation of Bionic Rudder With Leading-Edge Protuberances

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Hongtao Gao ◽  
Wencai Zhu
Keyword(s):  
Electron Microscopy ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Spanwise Direction ◽  
Flow Mechanism ◽  
Suction Surface ◽  
Edge Profile ◽  
Drag Ratio ◽  
Lift To Drag Ratio

The duck's webbed feet are observed by using electron microscopy, and observations indicate that the edges of the webbed feet are the shape of protuberances. Therefore, the rudder with leading-edge protuberances is numerically studied in the present investigation. The rudder has a sinusoidal leading-edge profile along the spanwise direction. The hydrodynamic performance of rudder is analyzed under the influence of leading-edge protuberances. The present investigations are carried out at Re = 3.2 × 105 and 8 × 105. In the case of Re = 3.2 × 105, the curves of lift coefficient illustrate that the protuberant leading-edge scarcely affects the lift coefficient of bionic rudder. However, the drag coefficient of the bionic rudder is markedly lower than that of the unmodified rudder. Therefore, the lift-to-drag ratio of the bionic rudder is obviously higher than the unmodified rudder. In another case of Re = 8 × 105, the advantageous behavior of the bionic rudder with leading-edge protuberances is mainly performed in the post-stall regime. The flow mechanism of the significantly increased efficiency by the protuberant leading-edge is explored. It is obvious that the pairs of counter-rotating vortices are presented over the suction surface of bionic rudder, and therefore, the flow is more likely to adhere to the suction surface of bionic rudder.

Design and analysis osculating general curved cone waverider

2017 ◽  
Vol 89 (6) ◽  
pp. 797-803 ◽  
Author(s):  
Xuzhao He ◽  
Jialing Le ◽  
Si Qin
Keyword(s):  
High Performance ◽  
Design Method ◽  
Design Methods ◽  
Hypersonic Vehicles ◽  
Exit Plane ◽  
Content Type ◽  
Volumetric Characteristics ◽  
Flow Compression ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Purpose Waverider has high lift to drag ratio and will be an idea aerodynamic configuration for hypersonic vehicles. But a structure permitting aerodynamic like waverider is still difficult to generate under airframe’s geometric constrains using traditional waverider design methods. And furthermore, traditional waverider’s aerodynamic compression ability cannot be easily adjusted to satisfy the inlet entrance requirements for hypersonic air-breathing vehicles. The purpose of this paper is to present a new method named osculating general curved cone (OCC) method aimed to improve the shortcomings of traditional waveriders. Design/methodology/approach A basic curved cone is, first, designed by the method of characteristics. Then the waverider’s inlet captured curve and front captured tube are defined in the waverider’s exit plane. Osculating planes are generated along the inlet captured curve and the designed curved cone is transformed to the osculating planes. Streamlines are traced in the transformed curved cone flow field. Combining all streamlines which have been obtained, OCC waverider’s compression surface is generated. Waverider’s upper surface uses the free stream surface. Findings It is found that OCC waverider has good volumetric characteristics and good flow compression abilities compared with the traditional osculating cone (OC) waverider. The volume of OCC waverider is 25 per cent larger than OC waverider at the same design condition. Furthermore, OCC waverider can compress incoming flow to required flow conditions with high total pressure recovery in the waverider’s exit plane. The flow uniformity in the waverider exit plane is quite well. Practical implications The analyzed results show that the OCC waverider can be a practical high performance airframe/forebody for hypersonic vehicles. Furthermore, this novel waverider design method can be used to design a structure permitting aerodynamic like waverider for a practical hypersonic vehicle. Originality/value The paper puts forward a novel waverider design method which can improve the waverider’s volumetric characteristics and compression abilities compared with the traditional waverider design methods. This novel design approach can extend the waverider’s applications for designing hypersonic vehicles.

Pure Yaw Simulations of Fast Delft Catamaran 372 in Deep Water

2020 ◽  
Author(s):  
Suleyman Duman ◽  
Sakir Bal
Keyword(s):  
Deep Water ◽  
High Speed ◽  
Point Of View ◽  
Hydrodynamic Performance ◽  
Marine Vehicles ◽  
Wave Interference ◽  
Force Moment ◽  
Unsteady Rans ◽  
Cfd Method ◽  
Turbulent Flow Conditions

Fast marine vehicles have become more important than ever before due to increasing need and population. In maritime sector, special ship types such as catamaran and trimaran have already been designed and/or built to the civil and naval areas of use. The hydrodynamic performance of these vessels is an interesting problem for naval architects due to the wave interference between the hulls. From this point of view, a generic high-speed catamaran hull form (Delft catamaran 372 or DC372) has been chosen for the numerical prediction of manoeuvring coefficients. To achieve this, the pure yaw captive manoeuvre simulations of the DC372 have been performed in deep water conditions at several oscillating frequencies by using CFD method. The unsteady RANS equations have been solved under incompressible, viscous and fully turbulent flow conditions. The uncertainty in the computations has been determined using proper techniques. Manoeuvring coefficients have been calculated by processing time dependent force/moment signals obtained numerically with the help of Fourier analysis. Due to the accurate grid structure used here, numerical ventilation has been prevented and wave deformations have been captured well.

Effects of Aspect Ratio on the Hydrodynamic Performance of Circular Cambered Otter Board

2018 ◽  
Author(s):  
Liuyi Huang ◽  
Yuyan Li ◽  
Jiqiang Xu ◽  
Qingchang Xu ◽  
Fenfang Zhao ◽  
...  
Keyword(s):  
Lift Coefficient ◽  
Flow Distribution ◽  
Full Scale ◽  
Hydrodynamic Performance ◽  
High Lift ◽  
Aspect Ratios ◽  
Simulation Results ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Good Agreement

An otter board is an important device that provides a desired horizontal opening of a trawl net. A high lift coefficient or lift-to-drag ratio is required for an otter board to maintain fishing efficiency. In the present work, the hydrodynamic performance of a circular cambered otter board was studied by numerical simulation, including the effects of aspect ratios (AR), and flow distribution around the otter board. Model tests were conducted in the flume tank as well as a comparison to the numerical results. It showed that simulation results exhibited very good agreement with experiment results. Results demonstrated that the model otter board had a critical angle of attack (AOA) of 50° (when the stall appeared). The maximum lift coefficient and lift-to-drag ratio of the model otter board were 2.421 and 3.719, respectively. However, the maximum values of the full-scale otter board increased first and then decreased with an increasing AR. And the full-scale otter board had a better performance when AR = 2.489, it can enhance the lift coefficient by 17.4% compared with the initial otter board (AR = 1.25). In addition, the flow distribution around the otter board showed that the flow was smooth at small AOAs, when it attacked at large AOA (exceeded 55°), flow separation and eddies were appeared at the lee-side of the otter board.

scholarly journals Vibration and Performance Analyses Using Individual Blade Pitch Controls for Lift-Offset Rotors

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Jae-Sang Park ◽  
Do-Hyung Kim ◽  
Sanghyun Chae ◽  
Ye-Lin Lee ◽  
Jeong-In Go
Keyword(s):  
Phase Angle ◽  
High Speed ◽  
Actuation Frequency ◽  
Control Phase ◽  
Coaxial Rotor ◽  
Compound Helicopter ◽  
And Performance ◽  
And Control ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This work attempts to reduce the hub vibratory loads of a lift-offset rotor using IBC (individual blade pitch control) in high-speed forward flight. As a lift-offset rotor for the present study, the rigid coaxial rotor of a XH-59A compound helicopter is considered and CAMRAD II is used to predict the hub vibration and rotor performance. Using the IBC with a single harmonic input at 200 knots, the vibration index of the XH-59A rotor is minimized by about 62% when the 3/rev actuation frequency is applied with the IBC amplitude of 1° and control phase angle of 270° (3P/1°/270°); however, the rotor effective lift-to-drag ratio decreases by 3.43%. When the 2/rev actuation frequency with the amplitude of 2° and control phase angle of 270° (2P/2°/270°) and the 3/rev actuation frequency using the magnitude of 1° and control phase angle of 210° (3P/1°/210°) are used in combination for the IBC with multiple harmonic inputs, the vibration index is reduced by about 62%, while the rotor effective lift-to-drag ratio increases by 0.37% at a flight speed of 200 knots. This study shows that the hub vibration of the lift-offset rotor in high-speed flight can be reduced significantly but the rotor performance increases slightly, using the IBC with multiple harmonic inputs.

scholarly journals An Aerodynamic Design Method to Improve the High-Speed Performance of a Low-Aspect-Ratio Tailless Aircraft

2021 ◽  
Vol 11 (4) ◽  
pp. 1555
Author(s):  
Zhongyuan Liu ◽  
Lie Luo ◽  
Binqian Zhang
Keyword(s):  
Aspect Ratio ◽  
High Speed ◽  
Design Method ◽  
Aerodynamic Performance ◽  
Pitching Moment ◽  
Aerodynamic Design ◽  
Linear Superposition ◽  
Low Aspect Ratio ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper puts forward an aerodynamic design method to improve the high-speed aerodynamic performance of an aircraft with low-aspect-ratio tailless configuration. The method can ameliorate the longitudinal moment characteristics of the configuration by designing and collocating the key section airfoils with the constrains of fixed parameters of planform shape and capacity. Firstly, the effect of twisting the wing, fore-loading and aft-reflexing key section airfoils on the high-speed aerodynamic performance of the configuration is evaluated by high-fidelity numerical methods, and quantified by defining trimming efficiency factors. Then, a linear superposition formula is obtained by analyzing the effect rule of trimming efficiency factor, and based on the formula the design and collocation methods of key section airfoils are achieved. According to the methods, a trimmed configuration is obtained. The results of computational fluid dynamics (CFD) and wind tunnel tests show that the trimmed configuration has smaller zero-lift pitching moment and higher available lift-to-drag ratio than the initial configuration at cruise, besides the trimmed configuration achieves the design principle raised for tailless configuration, which can be described as the zero-pitching moment, cruising design lift coefficient, and maximum lift-to-drag ratio are coincident. In addition, at off-design conditions, the trimmed configuration shows favorable drag divergence characteristics, satisfactory aerodynamic characteristics at medium-altitude maneuvering condition, and good stall and pitching-moment performance at low speed state.

Performance of S1210 Profile Used in Current Turbine Blades With Tubes Inserted at a Regular Interval

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Parikshit Kundu ◽  
Arunjyoti Sarkar ◽  
Vishwanath Nagarajan
Keyword(s):  
Flow Separation ◽  
Turbine Blades ◽  
Leading Edge ◽  
Suction Side ◽  
Current Speed ◽  
Separation Process ◽  
Hydrodynamic Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Current Turbine

Abstract The annual power output of a current turbine is affected by flow separation followed by the stall condition in an environment of varying current speed. Flow separation appears as the fluid in the boundary layer over the blade surface loses its kinetic energy. Delaying this separation process is essential to extract more power throughout the year considering the variation in the current speed. Several active and passive means are available in the literature today to achieve a delay in the flow separation process. Inserting tubes in an aero/hydrofoil at a constant spacing, connecting the fluid near the leading edge and a downstream location on the suction side is a novel approach that has been numerically investigated here. The baseline profile chosen here is S1210, which is used in the current turbine blades. The hydrodynamic performance of the profile with tubes has been compared with the baseline profile in terms of the force coefficients, lift to drag ratio, and stall angle. The maximum lift has been noticed to be increased by 18% and the stall is delayed by 2 deg (from 10 deg to 12 deg). The maximum lift to drag ratio is increased by 130% at 12 deg (beyond the stall of the baseline profile). The results show that the insertion of tubes can make the existing profile more efficient for the stated application.

Effects of Curvature on Slamming Loads

2016 ◽  
Author(s):  
John B. Weber ◽  
Raj Das ◽  
Mark Battley
Keyword(s):  
High Speed ◽  
High Performance ◽  
Experimental Studies ◽  
Rigid Bodies ◽  
Small Scale ◽  
Marine Vehicles ◽  
Numerical Studies ◽  
Impact Forces ◽  
Structural Responses ◽  
Peak Impact Force

Much research has been directed at understanding and predicting water slamming loads for a range of geometries of varying rigidity and size. Analytical and numerical studies focused on slamming of cylindrical rigid bodies are present in literature but there are relatively few experimental studies useful for validation purposes, none of which methodically investigate a range of curvatures. Despite the current understanding of slamming loads and structural responses, high speed marine vehicles still experience slamming related failures in operation. In this study, nominally rigid, singly curved prismatic specimens of varying curvature are subjected to constant velocity water impacts relevant to those encountered by high performance offshore racing yachts and other high-speed craft. Peak impact forces of 14 to 52 kN were recorded while testing specimens with radii ranging from 0.300 to 5.000 m. Experimental peak impact force and event impulse are found to be significantly lower than predicted by numerical and small scale empirically derived methods. A modification is introduced which improves the empirical model.

Magnetic Levitation Forces—Circular Coils

1973 ◽  
Vol 51 (7) ◽  
pp. 731-736
Author(s):  
P. A. Puhach ◽  
D. L. Atherton ◽  
B. Castel
Keyword(s):  
Vector Potential ◽  
High Speed ◽  
Magnetic Levitation ◽  
Magnetic Vector Potential ◽  
Magnetic Vector ◽  
Drag Forces ◽  
Circular Coil ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Magnetic vector potential is used to derive lift and drag forces for arbitrary coils moving parallel to infinite conducting slabs. It is shown that at high speed the ratio of magnetic lift-to-drag forces for a circular coil whose diameter is small in comparison with its height above the conducting slab becomes 0.6763(hλ)1/2, where λ = μσv. It is concluded that, in practice, the rounded corners needed on rectangular levitation coils will not alter the magnetic lift-to-drag ratio significantly.

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