Computational fluid dynamics (CFD) study was done on the propeller design of a micro aerial vehicle (quadrotor-typed) to optimize its Aerodynamic performance via Shear Stress Transport K-Omega (SSTk-w)turbulence model. The quadrotor model used was WL-V303 Seeker. The design process started with airfoils selection and followed by the evaluation of drone model in hovering and cruising conditions. To sustain a 400g payload, by Momentum Theory an ideal thrust of 5.4 N should be generated by each rotor of thequadrotor and this resulted in an induced velocity of 7.4 m/s on the propeller during hovering phase, equivalent to Reynolds number of 10403 at 75% of the propeller blade radius. There were 6 propellers investigated at this Reynolds number. Sokolov airfoil which produced the largest lift-to-drag ratio was selected for full drone installation to be compared with the original model (benchmark). The CFD results showed that the Sokolov propeller generated 0.76 N of thrust more than the benchmark propeller at 7750 rpm.Despite generating higher thrust, higher drag was also experienced by the drone installed with Sokolov propellers. This resulted in lower lift-to-drag ratio than the benchmark propellers. It was also discovered that the Aerodynamic performance of the drone could be further improved by changing the rotating direction of each rotor. Without making changes on the structural design, the drone performance increased by 39.58% in terms of lift-to-drag ratio by using this method.

This paper aimed at presenting a number of suggested improvements that can enhance the performance of a multi-rotor Unmanned Aerial Vehicle. Evaluating each suggestion in terms of the added benefits and feasibility concluded a final choice, which is incorporating a sinusoidal leading-edge profile to the propeller. This choice was numerically investigated with ANSYS Fluent 16. 1 through the SST K-Omega turbulence model. The performance of the modified propeller was assessed by comparing the lift and drag results to the same propeller with a straight leading-edge under the same conditions. Both models were studied at pre-stall and post-stall conditions to see the performance effect with respect to the angle of attack. The findings of this research showed 7% increase in the lift force and coefficient that were associated with the addition of the sinusoidal leading-edge including improved recovery from stall spanning from angle of attack that extends between 10° to 25° . This research also provides more insights into how the delayed stall and improved lift help the multirotor to extend flight time and carry heavier payloads. It allows for the exploration of the inner working of the sinusoidal leading-edge and its relationship with the flow field over the propeller.

An efficient parallel strategy is presented for optimization of the Aerodynamic shapes using Genetic Algorithm (GA). The method is a hybrid Parallel Genetic Algorithm (PGA) that combines a multi-population PGA and master-slave PGA using Message Passing Interface. GA parameters are firstly tuned according to the fact that subpopulations evolve independently. The effect of the number of sub-population on the computational time is investigated. Finally, a new strategy is presented based on the load balancing that aims to decrease the idle time of the processors. The algorithm is used for optimization of a transonic airfoil. An unstructured grid finite volume flow solver is utilized for objective function evaluations. For the considered class of problems, the suggested Hierarchical Parallel Genetic Algorithm (HPGA) results in more than 30% reduction in optimization time in comparison to regular master-slave PGA. A semi-liner speed-up is also obtained which indicates that the model is suited for modern cluster work stations.

In this work, a modification has been made to increase the efficiency and convergence of the harmony search algorithm. Then, the capability of this amendment was investigated by applying it to the following Aerodynamic problems for the first time. First, the methods of airfoil shape parametrization (Bezier curves, Parsec method, and NACA 4-digit airfoil) were investigated using an inverse optimization design by the present modified harmony search optimization algorithm. Then, inverse and direct optimization of an airfoil were carried out by the modified algorithm. Aerodynamic analysis of the problem was obtained using compressible Reynolds-Averaged Navier-Stokes (RANS) equations along with the Spalart-Allmaras turbulence model. Results showed that the Bezier curves and the Parsec method have higher flexibility than the NACA 4-digit airfoil. The Parsec method was introduced as the best approach, because of fewer control parameters. The inverse optimization results showed that the present airfoil shape optimization set can obtain the target shape with high accuracy. The Direct optimization with a maximum lift to drag ratio target function revealed that the shock waves significantly weaken at the optimum airfoil. Generally, the results obtained verify that using the modified harmony search algorithm together with the Parsec method provides a powerful tool for direct and inverse Aerodynamic optimization.

In order to improve the performance of single-stage turbines, blade profiling optimization was conducted for the guide vane and rotor under design condition. Support vector regression (SVR) and non-dominated sorting genetic algorithm-II (NSGA-II) were used to execute the optimization, with the objective of maximizing the efficiency and total pressure ratio of single-stage turbines. The gas turbine chosen for the initial study was the KJ66, which is one of the most robust and primitive small gas turbine designs available. The influence mechanism of the stator and rotor profiling on flow field and performance was discussed. The results revealed that compared with the prototype, the adiabatic efficiency increased by 5. 95% and the total pressure ratio increased by 0. 9%. Furthermore, the matching of flows between the stator blade and rotor blade obviously improved. The optimized guide vane suppressed the flow separation by increasing the leading edge and improving the distribution of the inlet angle of attack. The load distribution of rotors with a 50% spanwise position changed from the original "C" loaded to post-loaded. The leading load obviously decreased, and the angle of attack was smaller than that of the prototype, which effectively weakened the flow separation at the leading edge of the rotor. Compared with the original rotor, the higher lean angle and pressure ratio of the turbine stage also improved. However, the leakage loss near the shroud of the rotor increased, which led to decreased efficiency.