Comparative Analysis of a High Bypass Turbofan using a Pulsed Detonation Combustor

It has been proposed that the implementation of a pulsed detonation combustor in a high-bypass turbofan engine would result in an engine that is both more efficient and more reliable. The validity of the performance claims are evaluated based on a comparison between the baseline and hybrid turbofans. The hybrid pulsed detonation engine was modeled in the Numerical Propulsion Simulation System (NPSS) and shares a common architecture with the baseline turbofan model, except that the combustor of the baseline engine is replaced with a pulsed detonation combustor. Detonation effects are calculated using a closed form solution of the Chapman-Jouguet Mach number with a total energy correction applied. Cycle time is calculated to provide a reasonable estimate of frequency for the user input geometry, and the losses due unsteady flow are accounted for by applying pressure and temperature losses to the fluid. A parametric study was performed to evaluate the effects of these losses on net thrust and TSFC. There is a definite level of acceptable loss that if surpassed makes pulsed detonation combustion a good candidate for inclusion into a hybrid turbofan engine

Design and Experimentation of a Premixed Rotating Detonation Engine

Desire for a more efficient air breathing engine has shifted research attention to the Rotating Detonation Engine (RDE). Detonation is a more efficient combustion process than deflagration and provides a pressure gain. The RDE detonation cycle occurs in a compact volume to produce a high specific impulse engine. Computational fluid dynamic (CFD) models have predicted higher specific impulse and detonation wave speeds than has been seen in experimental RDE. The CFD models frequently assume premixed reactants and ignore inlet geometries to facilitate rapid computation. An experimental premixed RDE was sought to test if the premixed assumption in CFD was the root cause of the discrepancy between computational and experimental results. Design of a successful premixed RDE employed a feed system that simultaneously arrested flashback into the premixture while it fed the detonation. Flashback arresting feed designs were explored with single injector tests and validated with a fully premixed RDE. A relationship between arresting length and detonation feed requirements was derived and used to design a premixed RDE that fed premixture through feed slots that were 2.5 cm long and 0.5 mm high and operated on ethylene fuel and air oxidizer. The premixed RDE operated within a narrower region of equivalence ratio than a non-premixed RDE. Chemiluminescence video indicated that the premixed RDE experience combustion reactant-product mixing, and supports the theory that mixing delays are the root cause of slower wave speeds in experimental RDE. Time averaged chemiluminescence results indicate that RDE detonations to not complete the reaction within the detonation wave, and suggest that future CFD studies should assume unmixed reactants, model the full injection geometry, and include a comprehensive chemical mechanism

Kinematic analysis of conically scanned environmental properties

A method for determining the velocity of features such as wind. The method preferably includes producing sensor signals and projecting the sensor signals sequentially along lines lying on the surface of a cone. The sensor signals may be in the form of lidar, radar or sonar for example. As the sensor signals are transmitted, the signals contact objects and are backscattered. The backscattered sensor signals are received to determine the location of objects as they pass through the transmission path. The speed and direction the object is moving may be calculated using the backscattered data. The data may be plotted in a two dimensional array with a scan angle on one axis and a scan time on the other axis. The prominent curves that appear in the plot may be analyzed to determine the speed and direction the object is traveling