Aerospace Science and Technology
Alireza Ekrami Kivaj; Alireza Novinzadeh; farshad pazooki; Ali Mahmoodi
Abstract
This study aims to investigate the spacecraft returning from the atmosphere. Due to high speed, prolonged flight duration, and numerical sensitivity, returning from the atmosphere is regarded as one of the more challenging tasks in route design. Our suborbital system is subjected to a substantial thermal ...
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This study aims to investigate the spacecraft returning from the atmosphere. Due to high speed, prolonged flight duration, and numerical sensitivity, returning from the atmosphere is regarded as one of the more challenging tasks in route design. Our suborbital system is subjected to a substantial thermal load as a result of its return at high speed and the presence of uncertainty. In addition, the current study aims to lessen the thermal load in the system to meet the needs of the initial and final conditions through multi-subject optimization, comparison of the two fields of aerodynamics and flight dynamics, assistance from optimal control theory, and consideration of uncertainties The heat load in the sub-orbital system could be reduced by around 9.6% using these algorithms and optimum control theory. Artificial bee colonies, genetic algorithms, and the combined genetic algorithms and particle swarm algorithms were utilized as exploratory optimization techniques. The objective of the flight mechanics system is also to create the best trajectory while taking into account uncertainty and minimizing thermal load. The conduction law based on heat reduction is described in the search for the ideal trajectory. We reduced the heat rate during the first part of the spacecraft's return journey from the atmosphere by concentrating on the angle of attack. By more accurately specifying the angle of attack and the angle of the bank in the second stage of the split guidance legislation, the ultimate return requirements could be achieved significantly .
Aerospace Science and Technology
Hossein Faveadi; Ali R. Davari; Farshad Pazooki; Majid Pouladian
Abstract
Flight simulation is a powerful and usefull instrument in design, testing, evaluation and validation of aircrafts; The results of aerolastic simulation along with rigid simulation can be used in the many areas of designs, such as modification or optimization, stability analysis and evaluating field test ...
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Flight simulation is a powerful and usefull instrument in design, testing, evaluation and validation of aircrafts; The results of aerolastic simulation along with rigid simulation can be used in the many areas of designs, such as modification or optimization, stability analysis and evaluating field test data; It can be said that the use of simulation in the fields of design and optimization, especially during the initial and detailed design, should be considered more than other fields; In this research, by use of simulation, the effect of some design parameters such as slenderless ratio, maneuvering acceleration, propulsion curve, natural frequency of the structure, aerodynamic load distribution , etc. On issues such as flight and tracking behavior, stability and collision accuracy, has been examined; In cases such as: evaluating the initial error or veviation of the thurst vector or its curve, rolling speed, tracking of control commands, etc. aerolastic simulation gives a more realistic output compared to rigid simulation; Further more in cases such as investigating the effect of aerodynamic load distribution or stiffness ans and mass distribution, only aerolastic simulation is able to respond. Accordingly, the main orientation of this research is to develop an approach with acceptable accuracy and speed in order to simulate elastic projectiles in order to achieve some of the mentioned goals; However, due to the wide range of effective parameters and their interaction, in this study, only the role of thrust and body rigidity has been examined.
Aerospace Science and Technology
Karim Dastgerdi; Farshad Pazooki; Jafar Roshanian
Volume 12, Issue 2 , October 2019, , Pages 61-70
Abstract
airplane in presence of asymmetric left-wing damaged. Variations of the aerodynamic parameters, mass and moments of inertia, and the center of gravity due to damage are all considered in the nonlinear mathematical modeling. The proposed discrete-time nonlinear MRAC algorithm ...
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airplane in presence of asymmetric left-wing damaged. Variations of the aerodynamic parameters, mass and moments of inertia, and the center of gravity due to damage are all considered in the nonlinear mathematical modeling. The proposed discrete-time nonlinear MRAC algorithm applies the recursive least square (RLS) algorithm as a parameter estimator as well as the error between the real damaged dynamics and a model of nominal undamaged aircraft to generate the desired control commands. The discrete-time adaptive control algorithm is augmented with a Nonlinear Dynamic Inversion (NDI) control strategy and is implemented on the NASA generic transport model (GTM) airplane while considering the effect of wing damage and un-modeled actuator dynamics. The stability of the proposed nonlinear adaptive controller is demonstrated through Popov’s hyperstability theory. Simulation results of the introduced controller are compared with the classical discrete-time adaptive control strategy. The results demonstrate the effective performance of the proposed algorithm in controlling the airplane in presence of abrupt asymmetric damage.
