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.

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.

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 Analysis of control programs and climb paths of the hypersonic first stage of an aerospace system

2019 ◽  
Vol 18 (1) ◽  
pp. 18-29 ◽  
Author(s):  
V. L. Balakin ◽  
M. M. Krikunov
Keyword(s):  
Optimal Control ◽  
Heat Flux ◽  
Traditional Approach ◽  
Angle Of Attack ◽  
Optimization Approach ◽  
Hypersonic Velocity ◽  
Optimal Angle ◽  
Control Programs ◽  
Peak Heat Flux ◽  
Mission Profile

Control programs and flight paths of the hypersonic first stage of an aerospace system in climb with acceleration to hypersonic velocity are analyzed. Two approaches to determining the control programs and flight paths are identified: the "traditional" approach and the "optimization" one. The "traditional" approach implies specifying a typical mission profile with max-q and peak heat flux. In the case of the "optimization" approach the problem of propellant mass minimum is stated and solved using the method of Pontryagin’s maximum principle. It concerns the mass of propellant consumed in hypersonic acceleration for various terminal flight path angles. Optimal control programs and optimal flight paths are determined. Those meeting the max-q and peak heat flux requirements are selected. The results of modeling the motion of a hypersonic booster with typical and optimal angle-of-attack schedules corresponding to the "traditional" and "optimization" approaches are presented and discussed. It is established that less propellant is consumed in the case of optimal control, which is accounted for by more efficient use of the hypersonic booster's aerodynamic performance due to direct control of the angle of attack.

scholarly journals Development and Application of Computational Tool Using Local Surface Inclination Methods for Preliminary Analysis of Hypersonic Vehicles

2020 ◽  
Author(s):  
Tiago Cavalcanti Rolim ◽  
Sheila Cristina Cintra ◽  
Marcela Marques da Cruz Pellegrini
Keyword(s):  
Preliminary Analysis ◽  
Aerodynamic Force ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Hypersonic Vehicles ◽  
Computational Tool ◽  
Local Surface ◽  
Force Coefficients ◽  
Surface Inclination

This work presents a computational tool for preliminary analysis of hypersonic vehicles, based on local surface inclination methods: the HipeX. This program was developed for reading standard triangulation language (STL) geometry files and calculating pressure coefficient and temperature distributions over vehicle’s surface using the Newtonian, modified Newtonian or tangent-wedge methods. Validations were made with a cylinder and a sphere, where only the Newtonian method was applied, and with experimental data from Apollo capsule at Mach 10, where the Newtonian and the modified Newtonian methods were applied. These validations presented the code capability to read geometries as well as to estimate aerodynamic force coefficients. A preliminary application was to predict the aerodynamic force coefficients of a generic hypersonic vehicle over constant dynamic pressure trajectories of 23,940, 60,000 and 95,760 N/m2 with zero angle of attack. With a fixed dynamic pressure of 60,000 N/m2, this vehicle was tested over several Mach numbers and with angle of attack variation from -10 to 10 deg. Zero angle of attack investigation showed minor changes on the force coefficients with altitude, while the variation of angle of attack produced more pronounced variations on these parameters. Maximum flow temperatures over vehicle’s surface were estimated ranging from 850 to 5,315 K.

scholarly journals Aerodynamic assessment of axisymmetric launchers in the context of multidisciplinary optimisation

2020 ◽  
Vol 12 (1) ◽  
pp. 135-144 ◽  
Author(s):  
Alexandru-Iulian ONEL ◽  
Teodor-Viorel CHELARU
Keyword(s):  
Mathematical Model ◽  
Mach Number ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Force Coefficients ◽  
Optimisation Algorithm

The paper presents a fast mathematical model that can be used to quickly assess the aerodynamic force coefficients of axisymmetric launchers as functions of Mach number and angle of attack. The tool developed based on the proposed mathematical model can be used separately or it can be integrated in a multidisciplinary optimisation algorithm for a preliminary small launcher design.

Thermal and structural response of aerospike mounted on blunt-nose body

2020 ◽  
pp. 095441002097648
Author(s):  
Zhang ZhunHyok ◽  
Won CholJin ◽  
Ri CholUk ◽  
Kim CholJin ◽  
Kim RyongSop
Keyword(s):  
Aerodynamic Force ◽  
Coupling Effect ◽  
Angle Of Attack ◽  
Structural Response ◽  
Response Characteristic ◽  
Wave Drag ◽  
Hypersonic Vehicle ◽  
Loosely Coupled ◽  
Calculation Results ◽  
Blunt Nose

The inclusion of aerospike on blunt nose body of hypersonic vehicle has been considered to be the simplest and most efficient technique for a concurrent reduction of both aeroheating and wave drag due to hypersonic speed. However, the thermal and mechanical behavior of aerospike structure under the coupling effect of aerodynamic force and aeroheating remains unclear. In this study, the thermal and structural response of aerospike mounted on the blunt nose body of hypersonic vehicle was numerically simulated by applying 3 D fluid-thermal-structural coupling method based on loosely-coupled strategy. In the simulation, the angle-of-attack and the spike’s length and diameter are differently set as α = 0°–10°, L/D = 1–2 and d/D = 0.05–0.15, respectively. Through the parametric study, the following results were obtained. Firstly, the increase of vehicle’s angle-of-attack and spike’s length unfavorably affect the thermal and structural response of aerospike. Secondly, the increase of spike’s diameter can improve its structural response characteristic. Finally, the aerospike with the angle-of-attack of 0° and the length and diameter of L/D = 1 and d/D = 0.15, respectively, is preferred in consideration of the effect of flight angle-of-attack and spike’s geometrical structure on the thermal and structural response of spike and the drag reduction of vehicle. The numerical calculation results provide a technical support for the safe design of aerospike.

scholarly journals Numerical simulation of flapping airfoil with alula

2020 ◽  
Vol 12 ◽  
pp. 175682932097798
Author(s):  
Han Bao ◽  
Wenqing Yang ◽  
Dongfu Ma ◽  
Wenping Song ◽  
Bifeng Song
Keyword(s):  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Aerodynamic Performance ◽  
Geometric Parameters ◽  
Flight Performance ◽  
Relative Angle ◽  
Vertical Distance ◽  
Unsteady Effect ◽  
Flapping Airfoil

Bionic micro aerial vehicles have become popular because of their high thrust efficiency and deceptive appearances. Leading edge or trailing edge devices (such as slots or flaps) are often used to improve the flight performance. Birds in nature also have leading-edge devices, known as the alula that can improve their flight performance at large angles of attack. In the present study, the aerodynamic performance of a flapping airfoil with alula is numerically simulated to illustrate the effects of different alula geometric parameters. Different alula relative angles of attack β (the angle between the chord line of the alula and that of the main airfoil) and vertical distances h between the alula and the main airfoil are simulated at pre-stall and post-stall conditions. Results show that at pre-stall condition, the lift increases with the relative angle of attack and the vertical distance, but the aerodynamic performance is degraded in the presence of alula compared with no alula, whereas at post-stall condition, the alula greatly enhances the lift. However, there seems to be an optimal relative angle of attack for the maximum lift enhancement at a fixed vertical distance considering the unsteady effect, which may indicate birds can adjust the alula twisting at different spanwise positions to achieve the best flight performance. Different alula geometric parameters may affect the aerodynamic force by modifying the pressure distribution along the airfoil. The results are instructive for design of flapping-wing bionic unmanned air vehicles.

scholarly journals 2D Numerical Simulation Study of Airfoil Performance

2021 ◽  
Author(s):  
Nasser Shelil
Keyword(s):  
Experimental Data ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Wind Turbines ◽  
Aerodynamic Force ◽  
Angle Of Attack ◽  
Turbulence Models ◽  
Aerodynamic Characteristics ◽  
Operating Conditions ◽  
Ansys Fluent

Abstract. The aerodynamic characteristics of DTU-LN221 airfoil is studied. ANSYS Fluent is used to simulate the airfoil performance with seven different turbulence models. The simulation results for the airfoil with different turbulence models are compared with the wind tunnel experimental data performed under the same operating conditions. It is found that there is a good agreement between the computational fluid dynamics (CFD) predicted aerodynamic force coefficients with wind tunnel experimental data especially with angle of attack between −5° to 10°. RSM is chosen to investigate the flow field structure and the surface pressure coefficients under different angle of attack between −5° to 10°. Also the effect of changing air temperature, velocity and turbulence intensity on lift and drag coefficients/forces are examined. The results show that it is recommended to operate the wind turbines airfoil at low air temperature and high velocity to enhance the performance of the wind turbines.

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