Techno Press
Tp_Editing System.E (TES.E)
Login Search


aas
 
CONTENTS
Volume 8, Number 2, March 2021
 


Abstract
The unmanned aerial vehicle (UAV) is becoming popular from last two decades and it has been utilizing in enormous applications such as aerial monitoring, military purposes, rescue missions, etc. Hence, the present work focused on the design of the UAV wing considering the CH10 airfoil. In this paper, the computational fluid dynamic analysis on CH10 cambered airfoil has been conducted to achieve the preliminary results on the aerodynamic lift and drag coefficients. The airfoil has a chord length of 1 meter and has been subjected to low Reynolds numbers of 500 000, which is the standard operating Reynolds number for UAV wing design. The C-type fluid domain has been constructed at 30C upstream and downstream of the airfoil to initialize the boundary conditions. The angle of attack ranging from 0

Key Words
airfoil; CH10; NACA 2412; CFD simulation; aerodynamics, UAV; FVM; ANSYS

Address
Abdul Aabid: 1.) Department of Engineering Management, College of Engineering, Prince Sultan University, P.O. Box 66833,
Riyadh 11586, Saudi Arabia
2.) Department of Mechanical Engineering, Faculty of Engineering, International Islamic University Malaysia, 53100, Kuala Lumpur, Malaysia

Liyana Nabilah Binti Khairulaman and Sher Afghan Khan: Department of Mechanical Engineering, Faculty of Engineering, International Islamic University Malaysia, 53100, Kuala Lumpur, Malaysia

Abstract
Accurate inertia properties information is important to reach an optimized estimation of attitude and precise control of a rigid spacecraft. Unfortunately, the satellite is succumbing several influences that can affect the inertia properties, such as fuel consumption and sloshing. Thus, this work inspects the use of star tracker to estimate the attitude, angular velocity and moment of inertia for a rigid nadir pointing satellite by employing extended Kalman filter, without any prior information about the nominal inertia matrix. The proposed estimator is applied in nadir pointing mode and without any constant control torque to avoid the attitude tumbling during the estimation phase, which in turn leads to a catastrophic failure of the satellite mission. The simulation results are compared to three other approaches and validated by Monte Carlo method that elucidates the good performance of the suggested approach and demonstrates its efficiency in satellite inertia tensor and attitude estimation even in worst situations.

Key Words
extended Kalman filter; inertia tensor; satellite; star tracker

Address
Mohammed E. A. Cheriet, Abdellatif Bellar, Mohammed Y. Ghaffour, Akram Adnane and Mohammed A. SI Mohammed: Department of Space Mechanics Research, Satellite Development Center, BP 4065 Ibn Rochd USTO, Oran, Algeria


Abstract
This paper describes an investigation of the vibration of a cracked bio-composite beam reinforced with random short Alfa fibers using both analytical and experimental methods. The main novelty is the incorporation of local natural short fibers in the dynamic study of bio-based beams in the presence of a transverse crack. In addition, damping coefficient was predicted versus the crack length, crack position and fibers content. In the experimental model, tensile tests were made to predict Young's modulus and ultimate strength of specimens. After that, vibration tests were made to predict natural frequencies and damping coefficients versus crack depths, crack positions and fibers content. In the absence of similar experimental works on Alfa fibers, a simplified analytical model of flexural vibration has been developed to compare the results of experimental measurements. For different boundaries conditions, the linear fracture mechanics combined with Castigliano's theorem were used to estimate the local flexibility matrix at the cracked zone. For the natural frequencies, close agreement was found between the experimentally measured values and those given by the analytical model. From obtained results, we showed the increase in fiber content tends to reduce the strength and the natural frequencies of Alfa reinforced composite beams. Finally, we concluded that depth and position of the crack had a significant effect on the natural frequencies and damping coefficients of the bio-composite beam.

Key Words
Alfa fibers; cracked composite beam; flexural vibration; natural frequencies

Address
Yassine Adjal, Zouaoui Sereir and Rachid Benzidane: Laboratory of Composite Structures and Innovative Materials, Faculty of Mechanical Engineering, University of Science and Technology of Oran- Mohamed Boudiaf (USTO-MB), BP 1505 El M'naouer, USTO, Oran, Algeria

Aya Bendada: Laboratory of Applied Mechanics, Faculty of Mechanical Engineering,
University of Science and Technology of Oran Mohamed Boudiaf (USTO-MB), BP 1505 El M'naouer, USTO, Oran, Algeria


Abstract
The goal of this research is to evaluate the stall behavior of a high aspect ratio rectangular wing in ground effect using an unsteady vortex-lattice method with a Kirchhoff-based correction (UVLM-K), including how the lift coefficient achieved in stall is affected by dynamic ground effect. A flow separation algorithm based on the Kirchhoff-Helmholtz theory and a flow separation model presented by Fischenberg are applied. The code was validated using experimental data from previously published works. The stall behavior of a rectangular wing of aspect ratio of 8.587 formed with a NACA 4415 airfoil section was studied in static and dynamic ground effect. To obtain the empirical data required by the UVLM-K, the NACA4415 airfoil was simulated at fixed height aboveground using a finite-volume code solver. The wing simulation results have shown that the lift coefficient achieved by the wing in stall for takeoff and flare maneuvers are lower than those estimated at a fixed height above the ground. It can be concluded, based on the results obtained herein, that the stall behavior of a wing in dynamic ground effect depends on the history of the maneuver.

Key Words
unsteady aerodynamics; stall prediction; ground effect; computational fluid dynamics; take-off and landing; Kirchhoff flow theory

Address
Carlos A. Neves: Department of Mechanical Engineering, Universidad Simón Bolívar, Sartenejas Valley, Caracas 1080-A, Venezuela

Pedro J. Boschetti: Department of Industrial Technology, Universidad Simón Bolívar, Camuri Valley, Naiguatá 1163, Venezuela

Abstract
The forthcoming use of Orion for Mars landing stimulated Zuppardi to compute global aerodynamic coefficients in rarefied flow along an entry path. Zuppardi and Mongelluzzo also studied Aerodynamics of a blunt cylinder, provided with flapped fins, as a possible alternative to Orion for Mars Entry, Descent and Landing. Computer tests were carried out, in the altitude interval 60-100 km, by three codes: i) home made code computing the entry trajectory, ii) Direct Simulation Monte Carlo code (DS2V), solving 2D/axisymmetric flow field and computing local quantities, iii) Direct Simulation Monte Carlo code (DS3V) solving 3D flow field and computing global aerodynamic coefficients. The comparison of the aerodynamic behaviour of the two capsules in axisymmetric flow field verified that heat flux and wall temperature for the finned-cylinder are higher than those of Orion. The DS3V results verified that Orion is better than the finned-cylinder to produce an aerodynamic force for slowing down the capsule. On the contrary, the results indicated that the finned-cylinder is better in terms of attitude control capability. The purpose of the present paper is to compare Aerodynamics of: Orion, finned-cylinder, a hypothetical, winged space-plane in high altitude Mars entry path. Computations were carried out by means of the two above mentioned DSMC codes, along both orbit and direct entry trajectories. While the global aerodynamic coefficients of the space-plane are comparable with those of the finned cylinder, the aerodynamic and thermal stresses (or pressure, temperature and heat flux) at the nose stagnation point are higher for the space-plane. Therefore, the finned-cylinder seems to be a valid alternative to Orion.

Key Words
Mars space-plane; Orion capsule; finned-cylinder capsule; entry trajectory; direct simulation Monte Carlo method

Address
Gennaro Zuppardi: Department of Industrial Engineering – Aerospace Division,University of Naples "Federico II", Piazzale Tecchio 80, 80125 Naples, Italy

Giuseppe Mongelluzzo: 1.) Department of Industrial Engineering – Aerospace Division,University of Naples "Federico II", Piazzale Tecchio 80, 80125 Naples, Italy
2.) INAF – Osservatorio Astronomico di Capodimonte, Salita Moiariello, 16, 80131, Naples, Italy


Techno-Press: Publishers of international journals and conference proceedings.       Copyright © 2021 Techno-Press
P.O. Box 33, Yuseong, Daejeon 34186 Korea, Tel: +82-2-736-6800 (GAE, EAS, WAS, ANR) +82-42-828-7995 (SEM, SCS, SSS) Fax : +82-2-736-6801, Email: info@techno-press.com