Most models of aircraft trajectories are non-linear and stochastic in natureļ¼ and their internal parameters are often poorly defined. The ability to model, simulate and analyze realistic air traffic management conflict detection scenarios in a scalable, composable, multi-aircraft fashion is an extremely difficult endeavor. Accurate techniques for aircraft mode detection are critical in order to …
Tag Archive: Aerospace
Mar
12
Computational investigations of high frequency acoustics and instabilities in a single-element rocket combustor
The overall objective of the current research is to evaluate if and how computational fluid dynamics CFD) can enhance our understanding of combustion instability. Specifically, the first objective is to examine whether computational fluid dynamics models can, with the computational resources that are available today, replicate high amplitude, high frequency combustion instability phenomena without using …
Mar
11
Regenerative Power Optimal Reaction Wheel Attitude Control
The thesis work develops an instantaneous power optimal attitude control for a spacecraft utilizing an integrated reaction wheel-flywheel system allowing for energy storage and return. The control is generally formulated to utilize an arbitrarily large number of reaction wheels, and is applicable to any system with redundant wheels spanning three-dimensional space. This is accomplished by …
Mar
11
Simulation and modeling of an acoustically forced model rocket injector
A numerical and experimental study was performed to assess the capability of the Loci-CHEM CFD solver in simulating dynamic interaction between hydrogen-oxygen turbulent diffusion flames and periodic pressure waves. Previous experimental studies involving a single-element shear-coaxial model injector revealed an unusual flame-acoustic interaction mechanism affecting combustion instability characteristics. To directly compare the simulation and experiments, …
Mar
10
Solid Propellant Microthruster Design, Fabrication, and Testing for Nanosatellites
This thesis describes the design, fabrication, and testing of a solid propellant microthruster (SPM), which is a two-dimensional matrix of millimeter-sized rockets each capable of delivering millinewtons of thrust and millinewton-seconds of impulse to perform fine orbit and attitude corrections. The SPM is a potential payload for nanosatellites to increase spacecraft maneuverability and is constrained …
Mar
10
Performance Evaluation of GPS L1/L2 Positioning with Partial Availability of the L2C Signals
The ongoing Global Positioning System GPS) modernization program has seen the deployment of a partial constellation of Block IIR-M or Block IIF satellites capable of transmitting the new L2C signal. There is great benefit for the low-cost civil receivers to generate L2C measurements on a second frequency in addition to the full availability of L1 …
Mar
10
Dynamic behavior of granular materials
An experimental technique has been developed that is capable of (1) controlling the triaxial stress state in the specimen, (2) dynamically loading the specimen in multiaxial compression, and (3) allowing the recovery of the sample after loaded by a single and well-defined pulse for the characterization of the failure mode. Hydrostatic pressure is introduced to …
Mar
10
Numerical investigation of the effects of continuum breakdown on hypersonic vehicle surface properties
A hypersonic vehicle crosses many regimes, from rarefied to continuum, as the vehicle descends through the atmosphere. This variation makes it difficult to simulate the flow since the physical accuracy of computational fluid dynamics CFD) can breakdown in rarefied flows and the direct simulation Monte Carlo DSMC) method is computationally expensive in continuum flows. This …
Mar
10
Linearly and nonlinearly optimized weighted essentially non-oscillatory methods for compressible turbulence
Weighted essentially non-oscillatory WENO) methods have been developed to simultaneously provide robust shock-capturing in compressible fluid flow and avoid excessive damping of fine-scale flow features such as turbulence. This is accomplished by constructing multiple candidate numerical stencils that adaptively combine so as to provide high order of accuracy and high bandwidth-resolving efficiency in continuous flow …
Mar
10
Design studies in fluid dynamics: I – Development of a low-speed wind tunnel II – Hydrodynamics of the exhaust duct of a hydrokinetic turbine
This thesis examines the optimization of two internal fluid flow paths: the design of a low-speed, open-circuit wind tunnel and the evaluation of the pressure-recovery performance through the exhaust duct of the Carleton Hydrokinetic Turbine. The wind tunnel is designed to provide highly uniform, low-turbulence test section flow at lower velocities than the existing Carleton …