Open Access. Powered by Scholars. Published by Universities.®
Aerodynamics and Fluid Mechanics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Aerodynamics and Fluid Mechanics
Channeling Influence On Noise And Aerodynamic Performance Of Naca 0012 Airfoil As A Possible Solution Of Wind Turbines Noise, Hussein Khudhayer Mohammad
Channeling Influence On Noise And Aerodynamic Performance Of Naca 0012 Airfoil As A Possible Solution Of Wind Turbines Noise, Hussein Khudhayer Mohammad
Dissertations
This work numerically and experimentally investigates the effect of using channels inside airfoils on the noise level as a possible resolution for aerodynamic noise generated by wind turbines. The work also investigates aerodynamic performance and turbulence around the employed airfoils. The results reveal that some of the samples show some improvement in reducing the aerodynamic noise. The reduction of the aerodynamic noise is explained as the trailing edge blowing injection that reduces the wake momentum deficit of the blade and reduces the pressure fluctuation which is responsible for noise production. Particularly, the angles of channel inclination with respect to the …
A Reinforcement Learning Approach To Spacecraft Trajectory Optimization, Daniel S. Kolosa
A Reinforcement Learning Approach To Spacecraft Trajectory Optimization, Daniel S. Kolosa
Dissertations
This dissertation explores a novel method of solving low-thrust spacecraft targeting problems using reinforcement learning. A reinforcement learning algorithm based on Deep Deterministic Policy Gradients was developed to solve low-thrust trajectory optimization problems. The algorithm consists of two neural networks, an actor network and a critic network. The actor approximates a thrust magnitude given the current spacecraft state expressed as a set of orbital elements. The critic network evaluates the action taken by the actor based on the state and action taken. Three different types of trajectory problems were solved, a generalized orbit change maneuver, a semimajor axis change maneuver, …
Global Skin Friction Diagnostics: The Glof Technique And Measurements Of Complex Separated Flows, Sudesh A. Woodiga
Global Skin Friction Diagnostics: The Glof Technique And Measurements Of Complex Separated Flows, Sudesh A. Woodiga
Dissertations
This work describes the application of the global luminescent oil film skin friction meter to quantitative global skin friction diagnostics of complex separated flows. The development of this technique is based on the relationship between the oil film thickness and luminescent intensity of a luminescent oil film. The projected thin oil film equation is given to relate the normalized luminescent intensity with skin friction. The variational formulation with a smoothness constraint on skin friction is proposed to obtain a snap shot solution from two consecutive images for a relative skin friction field. A complete skin friction field is reconstructed through …
Numerical Studies Of Transition For Flows Around Multi-Element Airfoils, Fengjun Liu
Numerical Studies Of Transition For Flows Around Multi-Element Airfoils, Fengjun Liu
Dissertations
The transition of flows around a multi-element airfoil has been numerically studied using RANS with a k - e two-equation transition model, LST and DNS. The transition model uses an effective eddy-viscosity by coupling an intermittence-like correction to a turbulence eddy-viscosity that can be obtained via solving a parent k - e turbulence model. The transition model is truly predictive in that it is able to predict transition onset locations without having to specify prior knowledge of the targeted transition process. The predicted transition onset locations for all the cases studied were compared with the measured data. The results suggest …