Title of Dissertation: Computational Investigation of Micro-Scale Coaxial Rotor Aerodynamics in Hover Vinod K. Lakshminarayan, Doctor of Philosophy, 2009 Dissertation directed by: Dr. James D. Baeder Department of Aerospace Engineering In this work, a compressible Reynolds-Averaged Navier Stokes (RANS) solver is extended to investigate the aerodynamics of a micro-scale coaxial rotor configurati...

The vortical structures in the rear separation and wake region produced by a micro-ramp that immersed in a supersonic turbulent boundary layer are investigated. The small scale separation was reveled close to the trailing edge and confirms the previous experimental observation. Between the reverse region and surrounding fast moving flow, a three-dimensional shear layer was formed, where vortice...

Turbulent solar convection is a source of various processes observed as large-scale active phenomena, e.g., coronal mass ejections, formation of self-organized magnetic structures that appear on the surface as sunspots and pores, and other non-linear dynamical structures and phenomena. Modern realistic numerical simulations of solar turbulent phenomena are based on first physical principles and...

In this study, electro-thermo-mechanical nonlinear vibration and instability of embedded piezoelectric micro-tube is carried out based on nonlocal theory and nonlinear Donnell's shell model. The smart micro-tube made of Poly-vinylidene fluoride (PVDF) is conveying an isentropic, incompressible fluid. The detailed parametric study is conducted, focusing on the remarkable effects of mean flow vel...

The vortex tube is a structurally simple device with no moving parts that is capable of separating a highpressure flow into two lower pressure flows with different energies, usually manifested as a difference in temperatures. The vortex tube is relatively inefficient as a stand-alone cooling device but it may become an important component of a refrigeration system when employed as an alternativ...

The vortex tube is device, which produces hot and cold air streams simultaneously at its two ends from a source of compressed air without any moving part. Literature review of this paper is to understand the effect of various parameters like inlet pressure of air, number of nozzles, cold orifice diameter and hot end valve angle on the performance of vortex tube. Also by the literature review it...

Shock/boundary layer interaction (SBLI) is an undesirable phenomenon, occurring in high-speed propulsion systems. The conventional method to manipulate and control SBLI is using a bleed system that involves the removal of a certain amount of mass of the inlet flow to control boundary layer separation. However, the system requires a larger nacelle to compensate the mass loss, larger nacelles con...

Optical vortex beams, generated by Diffractive Optical Elements (DOEs), are capable of creating optical traps and other multi-functional micromanipulators for very specific tasks in the microscopic scale. Using the Fibonacci sequence, we have discovered a new family of DOEs that inherently behave as bifocal vortex lenses, and where the ratio of the two focal distances approaches the golden mean...

In this study, artificial neural networks have been used to model the effects of four important parameters consist of the ratio of the length to diameter, the ratio of the cold outlet diameter to the tube diameter, inlet pressure, and cold mass fraction on the cooling performance of counter flow vortex tube. In this approach, experimental data have been used to train and validate the neural net...