Optimal Angle of Attack Control for Aerocapture

2022 ◽  
Author(s):  
Joshua K. Geiser ◽  
Daniel A. Matz
Keyword(s):  
Angle Of Attack ◽  
Optimal Angle

A Numerical Investigation of High Lift Coefficient Airfoils Near Regions of Stall

2013 ◽  
Author(s):  
Ravon Venters ◽  
Brian Helenbrook
Keyword(s):  
Experimental Data ◽  
Free Stream ◽  
Numerical Models ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Optimal Placement ◽  
Navier Stokes ◽  
Cross Sectional ◽  
High Lift ◽  
Optimal Angle

The cross-sectional geometry of a diffuser-augmented wind turbine (DAWT) is often that of a cambered airfoil oriented at an angle of attack such that the lift coefficient of the airfoil is maximal. Beyond this angle separation occurs, and the performance decreases. Thus, predicting this transition is important for creating an optimally designed diffuser. The focus of this work is to validate two numerical methods for predicting the onset of separation for highly cambered airfoils. The numerical models investigated are a Reynolds-averaged-Navier-Stokes (RANS) k–ε model and XFOIL. The results were compared to each other and to experimental data. Overall the most accurate model was the k–ε model. Using this model, an optimization of a 2D DAWT was performed which determined the optimal placement of the diffuser. This optimization showed that the optimal angle of attack for the diffuser is much greater than what one would expect based on the maximum lift angle of an airfoil in a free-stream.

scholarly journals Disturbed motion of a hypersonic vehicle in climb

2019 ◽  
Vol 18 (2) ◽  
pp. 7-20 ◽  
Author(s):  
V. L. Balakin ◽  
M. M. Krikunov
Keyword(s):  
Optimal Control ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Hypersonic Vehicle ◽  
Atmospheric Density ◽  
Optimal Angle ◽  
Control Programs ◽  
Target Values ◽  
Standard Values ◽  
Disturbed Motion

Disturbed motion of a hypersonic vehicle in climb is analyzed. Deviations of atmospheric density from standard values and deviations of aerodynamic force coefficients from nominal values are taken as disturbances. Disturbed motion of a hypersonic vehicle with the optimum angle-of-attack schedule and nominal flight characteristics is modeled. Deviations of terminal conditions of disturbed motion from the target values of velocity, altitude and path inclination are determined. Using the method of Pontryagin’s maximum principle the problem of fuel mass minimum consumed in hypersonic acceleration climb is solved for disturbed motion. Optimal angle-of-attack schedules, optimal flight paths and finite values of the hypersonic vehicle’s mass are determined. Comparative analysis of optimal control programs and flight paths obtained for disturbed and undisturbed motion is carried out.

Optimum Release Conditions for the New Rules Javelin

1987 ◽  
Vol 3 (3) ◽  
pp. 207-221 ◽  
Author(s):  
Mont Hubbard ◽  
LeRoy W. Alaways
Keyword(s):  
Angular Velocity ◽  
Initial Conditions ◽  
Angle Of Attack ◽  
Pitching Moment ◽  
Velocity Change ◽  
Optimal Angle ◽  
Rule Change ◽  
Speed Range ◽  
Main Effects ◽  
Aerodynamic Lift

Changes in the rules for construction of the men's javelin have dramatically altered the pitching moment profile as a function of angle of attack. Thus the optimal release conditions are different for the new javelin. Optimal release conditions are presented for nominal release velocities in the range 20 < vn < 35 m/s. Although the optimal release angle remains roughly constant near 30° over this speed range, the optimal angle of attack and pitching angular velocity change substantially with speed. The main effects of the rule change have been (a) to decrease the achievable range at a nominal velocity vn = 30 m/s by about 10% by making it impossible to take advantage of the javelin's potentially large aerodynamic lift forces, and (b) to make the flight much less sensitive to initial conditions.

scholarly journals Disturbed motion of the hypersonic first stage of an aerospace system in climb

2019 ◽  
Vol 18 (3) ◽  
pp. 16-28
Author(s):  
V. L. Balakin ◽  
M. M. Krikunov
Keyword(s):  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Atmospheric Density ◽  
Optimal Angle ◽  
Control Programs ◽  
Target Values ◽  
Standard Values ◽  
Reference Atmosphere ◽  
Disturbed Motion

Disturbed motion of the hypersonic first stage of an aerospace system in climb is analyzed. Deviations of atmospheric density from standard values and deviations of aerodynamic force coefficients from reference values are taken as disturbances. Disturbance motion of the hypersonic first stage of a hypersonic vehicle with the optimal angle-of-attack schedule obtained for reference atmosphere and nominal aerodynamic characteristics is modeled. Deviations of terminal conditions of disturbed motion from the target values of velocity, altitude and flight path inclination are determined. The problem of minimum propellant mass consumed in the climb with acceleration to hypersonic velocity is solved for disturbed motion by the method of Pontryagin’s maximum principle. Optimal angle-of-attack schedules, optimal flight paths and finite values of the mass of the hypersonic first stage are determined. Comparative analysis of optimal control programs and flight paths for disturbed and undisturbed motion is made.

scholarly journals Lift and Drag Coefficient Map of NACA4415 Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012066
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Optimal Angle ◽  
Fluent Software ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The NACA4415 airfoil was numerically simulated with the help of the Fluent software to analyze its aerodynamic characteristics. Results are acquired as follows: The calculation accuracy of Fluent software is much higher than that of XFOIL software; the calculation result of SST k-ω(sstkw) turbulence model is closest to the experimental value; within a certain range, the larger the Reynolds number is, the larger the lift coefficient and lift-to-drag ratio of the airfoil will be, and the smaller the drag coefficient will be; when the angle of attack is less than the optimal angle of attack, the Reynolds number has less influence on the lift-to-drag coefficient and the lift-to-drag ratio; as the Reynolds number increases, the optimal angle of attack increases slightly, and the applicable angle of attack range for high lift-to-drag ratios becomes smaller.

scholarly journals Windcatcher Louvers to Improve Ventilation Efficiency

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4459
Author(s):  
Young Kwon Yang ◽  
Min Young Kim ◽  
Yong Woo Song ◽  
Sung Ho Choi ◽  
Jin Chul Park
Keyword(s):  
Wind Speed ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Fine Particles ◽  
Angle Of Attack ◽  
Dynamics Simulation ◽  
Test Results ◽  
Optimal Angle ◽  
Ventilation Efficiency ◽  
Time Required

Windcatcher louvers are designed to capture air flowing outside a building in order to increase its natural ventilation. There are no studies that have designed the shape of the louver to increase the natural ventilation efficiency of the building. This study aimed to conduct a computational fluid dynamics simulation and mock-up test of a Clark Y airfoil-type windcatcher louver designed to increase the natural ventilation in a building. The following test results were obtained. The optimal angle of attack of the airfoil was calculated via a numerical analysis, which demonstrated that the wind speed was at its highest when the angle of attack was 8°; further, flow separation occurred at angles exceeding 8°, at which point the wind speed began to decrease. The results of the mock-up test demonstrated that the time required to reduce the concentration of fine particles in the indoor air was 120 s shorter when the windcatcher was installed than when it was not, which indicating that the time to reduce particles represents a 37.5%reduction. These results can be seen as reducing the energy consumption of ventilation in the building because the natural ventilation efficiency is increased.

scholarly journals Disturbed transatmospheric motion of the first stage of an aerospace system

2020 ◽  
Vol 19 (3) ◽  
pp. 18-30
Author(s):  
M. M. Krikunov
Keyword(s):  
Optimal Control ◽  
Comparative Analysis ◽  
Reference Values ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Atmospheric Density ◽  
Optimal Angle ◽  
Force Coefficients ◽  
Control Programs

The paper deals with disturbed transatmospheric motion of the first stage of an aerospace system. Deviations of atmospheric density and deviations of aerodynamic force coefficients from reference values are taken as disturbances. Optimal angle-of-attack schedules for the first stage are specified. Comparative analysis of optimal control programs for disturbed and undisturbed motion is carried out.

Optimal angle of attack for untwisted blade wind turbine

2009 ◽  
Vol 34 (5) ◽  
pp. 1279-1284 ◽  
Author(s):  
Chalothorn Thumthae ◽  
Tawit Chitsomboon
Keyword(s):  
Wind Turbine ◽  
Angle Of Attack ◽  
Optimal Angle

Airfoil Shape and Angle of Attack Optimization Based On Bézier Curve and Multi-Island Genetic Algorithm

2021 ◽  
Author(s):  
Jiabing Wang ◽  
Chaochen Wang ◽  
Bowen Zhou ◽  
Linlang Zeng ◽  
Kun Yang
Keyword(s):  
Genetic Algorithm ◽  
Angle Of Attack ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Bézier Curve ◽  
Bezier Curve ◽  
Optimal Angle ◽  
Wide Range ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract In order to improve the aerodynamic performance of the airfoil, the airfoil shape and the angle of attack (AOA) are optimized at the same time by the Multi-island Genetic Algorithm in this paper. The goal of the optimization is to maximize the lift-to-drag ratio which is calculated by computational fluid dynamics method. The airfoil is parameterized by the Bézier curve. The thickness and the camber of airfoil are no longer restricted to ensure a wide range of airfoil generation. The airfoil is optimized under different Reynolds numbers. The optimized airfoils obtained by the unconstrained AOA method are compared with several standard airfoils. The results show that the maximum lift-to-drag ratio of the optimized airfoil is much greater than the compared airfoils, and the optimized airfoils have good aerodynamic characteristics in a wide range of angle of attack. By comparing with the optimized airfoils obtained by the constrained AOA method, it shows that the constrained AOA method can't guarantee that the pre-constrained angle of attack is the optimal angle of attack of the airfoil, nor can obtain the maximum lift-to-drag ratio airfoil of all angles of attack and all airfoils. However, by using the angle of attack as one of the optimization variables, these problems can be solved well.

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