Research projects
System Identification via wind tunnel testing (2022)
The process of modeling and simulation of UAVs flight dynamics is crucial for analyzing UAVs performance/stability characteristics and determining/validating their flight-control parameters. Typically, physics-based modeling and system identification are the most common approaches used for molding UAVs flight dynamics. Although physic-based simulation models provide estimates of UAV response prior to first flight, such approach is very labor intensive. This work presents a rapid and efficient procedure that exploits physics-based modeling approach for simulating the nonlinear six degrees-of-freedom flight dynamics of a tailless fixed-wing UAV. The modeling process follows a modular fashion where commercial of-the-shelf software, tools, and sensors are employed to build the necessary sub-models (i.e., geometric, mass-inertia, aerodynamic, propulsion, and actuator). Then, all sub-models are integrated in a simulation environment (i.e., Simulink) to allow predicting the UAV dynamic response that results from given control inputs. The complete flight dynamic model will be verified for correct operation via comparing simulated trim and natural flight modes with calculated analytical results. Finally, specific flight test will be performed to validate the developed simulation model for the case study UAV. The current work aims to facilitate the development, verification, and validation of accurate/reasonable physics-based simulation models of UAVs for flight mechanics characterization and control law tuning.
Helicopter rotor blade modeling Design and analysis (2020)
In this work, an unsteady model proposed for calculating the average lift, thrust, power requirements, torque and propulsive efficiency for rotary wings. The proposed model accounts for unsteady wake effects as well as viscous friction drag, Leading edge suction effect and Post stall. The results were compared with the classical blade element theory and experimental work conducted on the helicopter flight demonstration wind tunnel case study. The experimental data of 7A rotor case study (test point 312) is used for validation of the proposed model considering the control angles of the selected case. Also, a computational solver results (Host/elsA solver) are used for comparing with the proposed model results along with the experimental published data. An experimental work is performed by using a commercial remotely controlled helicopter (Raptor 50) in order to investigate the averaged thrust at different rotor rpm. The results are compared with the proposed model along with the blade element theory. The accurate values of the local loads can be used for preliminary design of helicopter rotors.
Publications:
Elastic Torsion Effects on Helicopter Rotor loading in Forward Flight, A Dayhoum, MY Zakaria, O E. Abdelhamid, AIAA Scitech 2020 Forum, 0507
Speculation of local aerodynamic loads on helicopter rotor blade in forward flight, A Dayhoum, MY Zakaria, AM Elshabka, OE Abdelhamid, IOP Conference Series: Materials Science and Engineering 610 (1), 012099
Unsteady Aerodynamic Modeling and Prediction of Loads for Rotary Wings in Forward Flight, Abdallah Dayhoum, Mohamed Y Zakaria, Omar E Abdelhamid, 2019/8/18, International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, Vol.59285, American Society of Mechanical Engineers
Design procedures for Fixed pitch propellers (2019)
In this effort, a sequential design procedures based on selected design parameters are used to design a propeller used for unmanned Ariel vehicles applications. Given the engine power in hand as well as the total aircraft drag, a complete aerodynamic design procedures are conducted on a broad range of propeller rpm, chord distribution and twist angle in an iterative process. The aerodynamic modeling in conjunction with the structural analysis is obtained. A complete graphical user interface is obtained and a 3-Dimensional drawing for the proposed designed propeller is implemented then a full scale model is fabricated.
Publications:
Aerodynamic Modeling and Design Procedures for Unmanned Aerial Vehicle Propeller, MY Zakaria, OE Abdelhameed, M Abdelghafaar, M Yassin, AIAA Scitech 2020 Forum, 0018
Wind Tunnel Testing of Dynamic Flapped Airfoil (2018)
Non-conventional lifting mechanisms have been proposed to perform agile missions. Exploiting these mechanisms requires accurate characterization of the unsteady aerodynamics and control laws. The step response and frequency response functions have been proposed and used to model the unsteady aerodynamics over maneuvering airfoils. The work done by Wagner, Prandtl, Theodorsen and Garrick described some fundamental physical concepts in understanding and modeling the unsteady aerodynamics. These concepts are usually incorporated with a potential flow framework and small disturbance theory to obtain analytical expressions of the flow quantities. Unsteady aerodynamics can result from several independent or combined motions such as: pitching, plunging and surging like birds. Work has been done to explore the associated phenomena related to those motions.
Publications:
Aerodynamic response of a NACA-0012 airfoil undergoing non-sinusoidal pitching waveforms, H Shehata, MY Zakaria, MR Hajj, CA Woolsey AIAA Scitech 2019 forum, 0303
Aerodynamic analysis of flapped airfoil at high angles of attack, H Shehata, M Zakaria, A Hussein, MR Hajj, 2018 AIAA aerospace sciences meeting, 0037
Design, Fabrication and Testing of Counter-rotating Ducted Fan (2018)
This project is with a collaboration with Dr. Ahmed Farid Nemnem, the idea is to follow a new aerothermodynamics procedure to design a contra-rotating ducted fan. The output power is calculated to be 40 Newtons.
Publications:
Contra-rotating Ducted Fan Aerothermodynamic Design Procedure for Unmanned Applications, AF Nemnem, MY Zakaria, AM Elzahaby, 2018 AIAA Information Systems-AIAA
Performance Analysis and Aerodynamic Modeling of Contra-Rotating Ducted fan UAV, MY Zakaria, AF Nemnem, K Gad, MM Abdelwahab, AIAA Scitech 2019 Forum, 1788
Design and Testing of Micro-Wind turbines (2017)
A wind tunnel testing was performed on a swirl type centimeter scale micro wind turbine. The output power density of the tested CSMWT is higher compared to the fan type having the same diameter.
Publications:
Experimental investigation and performance modeling of centimeter-scale micro-wind turbine energy harvesters, MY Zakaria, DA Pereira, MR Hajj, Journal of wind engineering and industrial aerodynamics 147, 58-65
Centimeter Scale Micro Wind Turbine Modelling Correction Using Wind Tunnel Experiments, MY Zakaria, AF Nemnem, A Dayhoum, T Elnady, A Elzahaby, AIAA Scitech 2019
Self-induced limit cycle oscillations of a composite beam (2016)
One important phenomenon that has been observed when it comes to aeroelastic performance of flexible wings is the effects of large wing deformations on the structural frequencies, aerodynamic loads, and aeroelastic response in terms of flutter speed and ensuing the limit cycle oscillations. We designed an energy harvester that exploits the fact that large deformations can reduce the flutter speed of a cantilever beam. Particularly, we subject a flexible composite beam, held at a static angle of attack at the beam root, to air flow. This setup has the advantage of dispensing of the secondary structure needed to induce the beam vibration as in previous setups. By setting the beam at a non-zero angle of attack, it is subjected to a differential aerodynamic loading which results in a uniform static deflection that has the shape of the first bending mode.
When this deflection is large enough, the geometric nonlinearities affects the beam's stiffness and induce a change in its natural frequencies, which, in turn, cause the torsional and second bending frequencies to coalesce. This coalescence results in self-induced flutter of the beam. Beyond this bifurcation, the combination of the static deflection and geometric and aerodynamic nonlinearities causes self-sustained limit cycle oscillations (LCO) of the beam that can be efficiently exploited for energy harvesting.