scholarly journals Optimal Skip Entry Trajectory for Lunar Return Vehicle with Trim-Flaps

2017 ◽  
Vol 2017 ◽  
pp. 1-7
Author(s):  
Yin Wang ◽  
Keming Yao
Keyword(s):  
Trajectory Optimization ◽  
Optimization Design ◽  
Lift Coefficient ◽  
Heat Rate ◽  
State Constraint ◽  
Skip Entry ◽  
Drag Ratio ◽  
Minimum Heat ◽  
Lift To Drag Ratio ◽  
Order State

A medium lift-to-drag ratio lunar return vehicle with trim-flaps is presented in this paper. The trajectory optimization design under heat-rate constrain for skip entry lunar return vehicle is analyzed. The optimization problem with a first-order state constraint is introduced. The trajectory applying the Pontryagin maximum principle under the performance of minimum heat is optimized, and the optimal expression of lift coefficient is derived. The simulation studies show that this research method can decrease the heat-rate effectively.

scholarly journals Study on Multi-Objective Optimization Design and Passive Control of Wind Turbine Airfoil

2019 ◽  
Author(s):  
Yong Peng ◽  
Jun Wang ◽  
Wei Wang ◽  
Guoqing Yin
Keyword(s):  
Optimization Design ◽  
Passive Control ◽  
Lift Coefficient ◽  
Multi Objective Optimization ◽  
Trailing Edge ◽  
Multi Objective ◽  
Blunt Trailing Edge ◽  
Trade Offs ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract. In this paper, the class-shape function transform (CST) parametric method is used to parameterize the airfoil configuration, and a new airfoil is randomly generated within a limited range. The 2D Reynolds-Averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) solver is used to compute the quantities such as lift-to-drag ratio. The multi-objective genetic algorithm performs multi-objective optimization design on the airfoil plane shape to achieve high lift-to-drag ratio with low drag in operating ranges of angle of attack, and finally obtains the Pareto optimal solution set. The mixed function of index method is used to increase the thickness of the trailing edge of the airfoil. From the multi-objective solutions and blunt trailing edge solutions which represent the best trade-offs between the design objectives, one can select a set of airfoil shapes with a low relative drag force and with improved aerodynamic performance. Taking a typical airfoil NACA4418 as an example. The results show that the optimized airfoil has a better pressure distribution than the original airfoil, effectively increasing the lift coefficient and reducing the drag coefficient. After thickening the trailing edge of the optimized airfoil, the results show that the lift coefficient is improved at all angles of attack and the stall is delayed. And the blunt trailing edge airfoil has better lift-to-drag characteristics than the original airfoil and the optimized airfoil.

scholarly journals Fluid–structure interaction simulation on flight performance of a dragonfly wing under different pterostigma weights

2021 ◽  
Vol 37 ◽  
pp. 216-229
Author(s):  
Yung Jeh Chu ◽  
Poo Balan Ganesan ◽  
Mohamad Azlin Ali
Keyword(s):  
Optimization Design ◽  
Fluid Structure Interaction ◽  
Spatial Location ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dragonfly Wing ◽  
Interaction Simulation ◽  
Wing Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The dragonfly wings provide insights for designing an efficient biomimetic micro air vehicle (BMAV). In this regard, this study focuses on investigating the effect of the pterostigma weight loading and its spatial location on the forewings of dragonfly by using the fluid–structure interaction simulation. This study also investigates the effect of change in the wing elasticity and density on the wing performance. The forewing, which mimics the real dragonfly wing, is flat with a 47.5 mm span and a 0.4 mm thickness. The wing was set to cruise at 3 m/s with a constant flapping motion at a frequency of 25 Hz. This study shows that a small increase of pterostigma loading (11% of wing weight) at the tip of the wing significantly improves the lift to drag ratio, CL/CD, which has 129.16% increment in comparison with no loading. The lift to drag ratio depends on the pterostigma location, pterostigma loading, elastic modulus and density. The results of this study can be used as a reference in future BMAV wing optimization design.

scholarly journals Aerodynamic and Vibration Characteristics of the Micro-Octocopter at Low Reynolds Number

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Xiaohua Zou ◽  
Mingsheng Ling ◽  
Wenzheng Zhai
Keyword(s):  
Reynolds Number ◽  
Load Capacity ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Vibration Characteristics ◽  
Low Reynolds ◽  
Vibration Performance ◽  
Drag Ratio ◽  
Lift To Drag Ratio

With the development of flight technology, the need for stable aerodynamic and vibration performance of the aircraft in the civil and military fields has gradually increased. In this case, the requirements for aerodynamic and vibration characteristics of the aircraft have also been strengthened. The existing four-rotor aircraft carries limited airborne equipment and payload, while the current eight-rotor aircraft adopts a plane layout. The size of the propeller is generally fixed, including the load capacity. The upper and lower tower layout analyzed in this paper can effectively solve the problems of insufficient four-axis load and unstable aerodynamic and vibration performance of the existing eight-axis aircraft. This paper takes the miniature octorotor as the research object and studies the aerodynamic characteristics of the miniature octorotor at different low Reynolds numbers, different air pressures and thicknesses, and the lift coefficient and lift-to-drag ratio, as well as the vibration under different elastic moduli and air pressure characteristics. The research algorithm adopted in this paper is the numerical method of fluid-solid cohesion and the control equation of flow field analysis. The research results show that, with the increase in the Reynolds number within a certain range, the aerodynamic characteristics of the miniature octorotor gradually become better. When the elastic modulus is 2.5 E, the aircraft’s specific performance is that the lift increases, the critical angle of attack increases, the drag decreases, the lift-to-drag ratio increases significantly, and the angle of attack decreases. However, the transition position of the flow around the airfoil surface is getting closer to the leading edge, and its state is more likely to transition from laminar flow to turbulent flow. When the unidirectional carbon fiber-reinforced thickness is 0.2 mm and the thin arc-shaped airfoil with the convex structure has a uniform thickness of 2.5% and a uniform curvature of 4.5%, the aerodynamic and vibration characteristics of the octorotor aircraft are most beneficial to flight.

Optimal Design of Wind Turbines Using BIAS, A Method of Multipliers Code

1988 ◽  
Author(s):  
B. D. Vick ◽  
W. Wrigglesworth ◽  
L. B. Scott ◽  
K. M. Ragsdell
Keyword(s):  
Optimal Design ◽  
Rough Surface ◽  
Wind Turbines ◽  
Lift Coefficient ◽  
Power Coefficient ◽  
Method Of Multipliers ◽  
High Lift ◽  
Small Wind Turbines ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract A method has been developed and is demonstrated which determines the chord and twist distribution for a wind turbine with maximum power coefficient. Only small wind turbines (less than 10 kilowatts) are considered in this study, but the method could be used for larger wind turbines. Glauert determined a method for estimating the chord and twist distribution that will maximize the power coefficient if there is no drag. However, the method proposed here determines the chord and twist distribution which will maximize the power coefficient with the effect of drag included. Including drag in the analysis does not significantly affect the Glauert chord and twist distribution for airfoils with a high lift coefficient at the maximum lift to drag ratio. However, if the airfoil has a fairly low lift coefficient at its maximum lift to drag ratio due to its shape or a rough surface then significant improvement can be obtained in power coefficient by altering the Glauert chord and twist distribution according to the method proposed herein.

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.

Effects of leading-edge bevel angle on the aerodynamic forces of a non-slender 50° delta wing

2005 ◽  
Vol 109 (1098) ◽  
pp. 403-407 ◽  
Author(s):  
J. J. Wang ◽  
S. F. Lu
Keyword(s):  
Delta Wing ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Relative Thickness ◽  
Aerodynamic Performances ◽  
Stall Angle ◽  
Drag Ratio ◽  
Low Speed Wind Tunnel ◽  
Lift To Drag Ratio ◽  
Blunt Leading Edge

Abstract The aerodynamic performances of a non-slender 50° delta wing with various leading-edge bevels were measured in a low speed wind tunnel. It is found that the delta wing with leading-edge bevelled leeward can improve the maximum lift coefficient and maximum lift to drag ratio, and the stall angle of the wing is also delayed. In comparison with the blunt leading-edge wing, the increment of maximum lift to drag ratio is 200%, 98% and 100% for the wings with relative thickness t/c = 2%, t/c = 6.7% and t/c = 10%, respectively.

Aerodynamic characteristics of breathing blunt nose configuration at hypersonic speeds

2016 ◽  
Vol 231 (5) ◽  
pp. 840-858 ◽  
Author(s):  
Yasumasa Watanabe ◽  
Kojiro Suzuki ◽  
Ethirajan Rathakrishnan
Keyword(s):  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Positive Pressure ◽  
Stagnation Region ◽  
Total Drag ◽  
Hypersonic Speeds ◽  
Drag Ratio ◽  
Lift To Drag Ratio ◽  
Blunt Nose

Breathing blunt nose technique is one of the promising methods for reducing the drag of blunt-nosed body at hypersonic speeds. The air, traversed by the bow shock positioned ahead of the nose, at the stagnation region is allowed to enter through a hole at the blunt-nose and ejected at the rear part (base region) of the body. This manipulation reduces the positive pressure over the stagnation regions of the nose and increases the pressure at the base, resulting in reduced suction at the base. The simultaneous manifestation of reducing the compression at the nose and suction at the base regions results in reduction of the total drag. The drag reduction caused by the breathing blunt nose technique has been measured in a Mach 7 tunnel. Also, the drag and flow field around the blunt-nosed body, with and without breathing hole, has been computed. The aerodynamic characteristics of the breathing blunt nose model obtained experimentally are compared with the CFD results. It is found that the breathing results in 5% reduction in drag. The lift coefficient also comes down for the model with breathing nose. But the lift-to-drag ratio is found to be the same for both the cases; the blunt-nosed body with and without nose-hole.

Lift Augmentation between Passive and Active Vortex Generator

2016 ◽  
Vol 851 ◽  
pp. 532-537
Author(s):  
Nur Faraihan Zulkefli ◽  
Zulhilmy Sahwee ◽  
Nurhayati Mohd Nur ◽  
Muhamad Nor Ashraf Mohd Fazil ◽  
Muaz Mohd Shukri
Keyword(s):  
Reynolds Number ◽  
Lift Coefficient ◽  
Vortex Generator ◽  
Leading Edge ◽  
Plasma Actuator ◽  
Triangular Shape ◽  
Subsonic Wind Tunnel ◽  
Different Types ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This study was conducted to investigate the performance of passive and active vortex generator on the wing’s flap. The triangular shape of passive vortex generator (VG) was developed and attached on the wing’s flap leading edge while the plasma actuator performed as active vortex generator. The test was carried out experimentally using subsonic wind tunnel with 300 angles extended flap. Three different types of turbulent flow; with Reynolds number 1.5 x105, 2.0 x105, and 2.6x105 were used to study the aerodynamics forces of airfoil with plasma actuator OFF. All Reynolds number used were below 1x106. The result indicated that airfoil with plasma actuator produced higher lift coefficient 12% and lift-to-drag ratio 5% compared to airfoil with passive vortex generator. The overall result showed that airfoil with plasma actuator produced better lift forces compared to passive vortex generator.

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.

Sign in / Sign up

Export Citation Format

Share Document