Air Flow Acceleration Effect on Water Droplet Flow Behavior in Solid Rocket Motor

Most of the available research on horizontal axis wind turbines focuses on either lab-scale (15-60 cm rotor diameter) or commercial large-scale (80-130 m rotor diameter). The current work fills this gap because residential-scale turbines will be one of the key technologies during the next ten years. The current administration promotes dependence on renewables to cut carbon footprint. Therefore, the present work runs wind tunnel experimentation and performs 48 numerical simulations to evaluate the performance of a residential scale wind turbine with a blade generated from GOE 447 airfoil at three wind speeds (7.5, 12.5, and 17.5 m/s). Three different vortex generator designs were tested when added on the suction side of a 7 m blade. Two of those designs produced more power than a baseline rotor does (7.2% and 10.9% more power than the baseline rotor were achieved at 12.5 m/s wind speed). Furthermore, three winglet designs were added to the baseline design to investigate their influence on power production. The 90°, 60°, and 30° cant angles produce 5.0%,7.9%, and 6.9% more power than the baseline design.

Experimental and Numerical Investigation of Vortex Generators and Winglets in Horizontal Axis Wind Turbine Blade Design

Hasan

Abousabae

Hamad

et al. 2022

Mechanical Erosion Investigation in Solid Rocket Motor Nozzle Through Droplet Breakup and Surface Tension Influence

Abousabae

Amano

2023

Erosion prediction of the solid propellent nozzle is vital for its design process. This erosion is caused by the impingement of agglomerated aluminum/aluminum oxide particles on the nozzle walls. Thus, a multi-phase numerical model is established based on the Eulerian-Lagrangian approach to model the aluminum particles burning inside the combustion chamber and simulate the mechanical erosion of the nozzle. The numerical model is validated against numerical and experimental results from the literature. Then it is simplified by eliminating the aluminum particles burning process as they do not reach the nozzle. The simplified model will be further used in modeling the agglomerates' breakup and predicting the mechanical erosion for aluminum particles with lower surface tension. The results showed that applying the Reitz-Diwakar breakup model reduces the erosion rate by 6.2% - 24% depending on the injected droplets. In addition, it was found that a decrease in the erosion rate by 1% to 4.5% can be achieved by reducing the aluminum additive's surface tension by 15%.

Influence of Aluminum Content and Agglomerates Initial Velocity on Erosion in Solid Rocket Motor

Abousabae,

Khalil,

Al Hamad

et al. 2024

Despite the aluminized propellants offering a high specific impulse, the challenge of nozzle erosion adversely impacts the rocket's performance and its potential for reusability. This study presents a numerical model aiming to predict the mechanical erosion of the propulsion chamber nozzle. The model employs an Eulerian/Lagrangian approach to simulate the complexity of the flow field within the rocket combustion chamber and the interactions between the continuous phase and particles. The model also includes a simplified representation of the aluminum particle combustion process, besides the consideration of secondary breakup phenomena in liquid droplets. Experimental and numerical data from the literature were used to validate the numerical model. Subsequently, the model was utilized to explore the impacts of increasing propellant aluminum content and varying particles' injection velocities on the nozzle mechanical erosion. The outcomes indicated that higher aluminum content leads to a 4-10% increase in nozzle erosion compared to the 15% content case. Furthermore, the aluminum particles tend not to fully burn within the combustion chamber and contribute to nozzle erosion. Lastly, particles with higher initial velocity at the inlet of the combustion chamber increase the nozzle mechanical erosion despite the observed decrease in incident mass flux.