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Ibrahim H.H.,Arab Aviation | Tawfik M.,Cairo University | Negm H.M.,Cairo University
JVC/Journal of Vibration and Control | Year: 2011

A new nonlinear finite element model is provided for the nonlinear flutter response of shape memory alloy (SMA) hybrid composite plates under the combined effect of thermal and aerodynamic loads. The nonlinear governing equations for moderately thick rectangular plates are obtained using first-order shear-deformable plate theory, von Karman strain-displacement relations and the principle of virtual work. To account for the temperature dependence of material properties, the thermal strain is stated as an integral quantity of thermal expansion coefficient with respect to temperature. The aerodynamic pressure is modeled using the quasi-steady first-order piston theory. Newton-Raphson iteration method is employed to obtain the thermal post-buckling deflection, while the linearized updated mode method is implemented in predicting the limit-cycle oscillation at elevated temperatures. Numerical results are presented to show the thermal buckling and flutter characteristics of SMA hybrid composite plates, illustrating the effect of the SMA volume fraction and pre-strain value on the aero-thermo-mechanical response of such plates. © 2010 The Author(s).

Nada T.R.,Arab Aviation | Hashem A.A.,Cairo University
Egyptian Journal of Remote Sensing and Space Science | Year: 2012

The function of the injector in a monopropellant thruster is to atomize the liquid hydrazine and to distribute it over the catalyst bed as uniformly as possible. A second objective is to place the maximum amount of catalyst in contact with the propellant in as short time as possible to minimize the starting transient time. Coverage by the spray is controlled mainly by cone angle and diameter of the catalyst bed, while atomization quality is measured by the Sauter Mean Diameter, SMD. These parameters are evaluated using empirical formulae. In this paper, two main types of injectors are investigated; plain orifice and full cone pressure swirl injectors. The performance of these two types is examined for use with blow down monopropellant propulsion system. A comprehensive characterization is given and design charts are introduced to facilitate optimizing the performance of the injector. Full-cone injector is a more suitable choice for monopropellant thruster and it might be available commercially. © 2012 National Authority for Remote Sensing and Space Sciences.

The objective of this study is investigating the impact of synthetic jet on the boundary layer and optimising the slot yaw angle (β). A rectangular synthetic jet with yaw angle relative to freestream is applied for flat plate boundary layer control. Various slot yaw angles are applied to find optimized amount and their impacts on the boundary layer are measured using a boundary layer probe with 2-D traversing system. The slot yaw angles are varied from 0°∼90°. The assessment carried out using non-dimensional velocity profiles and lateral relative velocity (u/U) contours. © Owned by the authors 2012.

Nada T.R.,Arab Aviation
Aeronautical Journal | Year: 2013

This paper presents a modified one dimensional model for the pulsed plasma thruster. The model takes into account the impact of thruster geometry and capacitor initial energy on plasma inductance and resistance, as well as the ablated mass per pulse. These three factors have significant impact on the performance of the thruster and have not been considered concurrently before. The model is verified by comparing the estimated specific impulse, impulse bit and thrust-to-power ratio with experimental measurements for space qualified thrusters. The maximum error is estimated to be about 8% when using the modified model, while the conventional snowplow model produces error up to about 70%. The modified model is then employed to generate design charts that would help in selecting the proper combination of thruster geometry and energy level in the preliminary design phase of a pulsed plasma thruster for different space missions.

Elkhweldi M.A.,Arab Aviation | Elmabrouk S.K.,University of Tripoli
IEOM 2015 - 5th International Conference on Industrial Engineering and Operations Management, Proceeding | Year: 2015

Risk assessment has always been the most challenging part of the risk management process for aviation operations. This paper investigates the risks involved in the Tripoli and Mitiga International Airport in Tripoli, Libya. This case study addresses the risks that may occur during aircraft flight operations. It also investigates the human performance during the ground and flight operations. The paper implements some countermeasures in order to avoid and/or eliminate the risks, and to make sure that all risks remain at an acceptable level. © 2015 IEEE.

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