Saad Riffat Qureshi

A series of experiments were performed using multiple configurations of hydrofoils to assess the energy harvesting capabilities present within the wake of streamlined bodies. The experiments were performed in a low-speed water tunnel, with energy harvesting assessed using a piezoelectric eel and imaging equipment. Half-sinusoidal undulations were introduced in different combinations on the leading and trailing edges of the hydrofoil. All hydrofoils utilized a NACA 0012 cross-sectional profile. A piezoelectric eel was placed at a variable distance downstream of the hydrofoil’s trailing edge, and the hydrofoil’s angle of attack (α) was varied in order to assess the variation in power generation. The maximum power output was achieved at x/c = 1–1.5 downstream of the trailing edge in all configurations. It was observed that harvested energy is dependent on the oscillation of the eel, α, the streamwise distance between the trailing edge of the hydrofoils and the eel, as well as the geometry of the hydrofoils. Particle image velocimetry was also performed on selected cases for which the recorded energy harvest was high. The results showed that the NACA 0012 base profile has a higher extractable energy capacity in its wake than do the serrated hydrofoils, which confirms the results found in the literature.

This paper compares various optimization techniques and objective functions to obtain optimum rocket engine performances. This research proposes a modular optimization framework that provides an optimum design for Gas Generator (GG) and Staged Combustion (SC) Liquid Propellant Rocket Engines. This process calculates the ideal rocket engine performance by applying seven different optimization techniques: Simulated Annealing (SA), Nelder Mead (NM), Cuckoo Search Algorithm (CSA), Particle Swarm Optimization (PSO), Pigeon-Inspired Optimization (PIO), Genetic Algorithm (GA) and a novel hybrid GA-PSO technique named GA-Swarm. This new technique combines the superior search capability of GA with the efficient constraint matching capability of PSO. This research also compares objective functions to determine the most suitable function for GG and SC cycle rocket engines. Three single objective functions are used to minimize the Gross Lift-Off Weight and to maximize Specific Impulse and the Thrust-to-Weight ratio. A fourth multiobjective function is used to simultaneously maximize both Specific Impulse and Thrust-to-Weight ratio. This framework is validated against a pump-fed rocket, and results are within 1% of the actual rocket engine mass. The results of this research indicate that PSO and GA-Swarm produce optimum results for all objective functions. Finally, the most suitable objective function to use while comparing these two cycles is the Gross Lift-Off Weight.

The interface debonding in carbon fiber-reinforced polymers is analyzed and evaluated using the extended finite element method (XFEM). In order to accurately evaluate the bonding properties between fibers and matrix, different tests were carried out, including the multiple tests for different orientations to study longitudinal, transversal, and shear properties of unidirectional carbon fiber-reinforced composites. Extensive experimentation has been performed in all the different groups and categories with different dimensions and parameters in order to ascertain the values of strength and the prediction of the damage to the structure. The experimental and numerical comparison provided significant trends and data to evaluate the mechanical properties of the interface. The values of stiffness and strength are compared and validated. Development of Representative Volume Element (RVE) for progressive damage model to these damage phenomena has already been performed as a feasibility study for the model, though it is not included in this particular paper. The results of this research for all the experimental and numerical sets can serve as reliable data in the microsimulation of devices and sensitive parameters that include carbon fiber-reinforced light metal matrix composites and makes a better investigative model that contributes to various conditions. It further offers an investigation of the microscopic deformation mechanisms in the composites.

In the aircraft industry, the ultimate goal in any component’s design is to minimize its weight, maximize its durability, and increasing its life while keeping its overall life cycle costs low. As technology is progressing, UCAVs are gaining more and more prominence as jet powered UCAVs are already taking to skies presenting a myriad of challenges. This is especially true in the case of Landing gears as greater crashworthiness is required in high-speed high payload UCAVs. As jet powered UCAVs have a higher touchdown velocity and thus a higher chance of failure. In this research, a category of unmanned combat aerial vehicles was picked. In that category, a number of reference unmanned combat aerial vehicles were selected to extract the required parameters and dimensions of their main landing gears from literature review and analysis. The main landing gear was then modeled in CAD. Simultaneously loading conditions were defined and loads were determined. The equivalent von mises and maximum principal stresses were obtained from finite element analysis for multiple materials using the finite element package ANSYS. These results were then in turn used to calculate the factor of safety. Furthermore, an impact analysis was carried out in this crashworthiness study using Explicit Dynamics in LS DYNA for the same material. The stress formulations and deformations in impact were highly non-linear and more realistic and accurate than in static structural. The results were then validated.