Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 25 for “"low-order model"”.
-
Some properties of a low-order model of atmospheric circulation
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1964.
-
Exploring global dynamics in a low order model of parallel shear flow
The study of the onset of turbulence in the flow of fluids, which are governed by the Navier-Stokes equations, has produced some famous instabilities e.g. Kelvin Helmholtz instability. An important, and as of yet mysterious, flow is Plane Couette flow in which turbulence is observable. Another …
-
Analysis of Stresses in Metal Sheathed Thermocouples in High-Temperature, Hypersonic Flows
Flow temperature sensing remains important for many hypersonic aerodynamics and propulsion applications. Flight test applications, in particular, demand robust and accurate sensing, making thermocouple sensors attractive. Even for these extremely well-developed sensors, the prediction of stresses …
-
Chaos in models of double convection
… concentrates on the derivation and analysis of low-order sets of ordinary differential equations (ODEs) that accurately describe the behaviour of a fluid in convective motion. A second-order set of ODEs is presented and analysed, and then related to a particular double convection problem …
-
Numerical simulation and modelling of the effect of film cooling on entropy noise in a stator blade row
… fundamental understanding of how film cooling flows interact with entropy waves, and their influence on entropy noise generation. A 2D numerical framework has been developed for preliminary understanding of the problem, and then analysis of the effect of film cooling on the entropy noise …
-
Impact of Total Temperature Probe of Geometry on Sensor Flow and Heat Transfer
… This work has led to the development of low-order models which can be used to calculate the performance of a total temperature probe as a first-order estimate. These low-order models require knowledge of the heat transfer to the total temperature sensor in order to calculate the probe …
-
Applications of axial and radial compressor dynamic system modeling
… are related by the underlying dynamic system modeling approach that is common in all of them. Two types of models are introduced, suitable for modeling the dynamic behavior of axial and centrifugal compression systems: a compact single semi-actuator disk model, Model I, and a new modular multi …
-
Shock estimation in supersonic vehicles
… Advanced designs can be realized by improving low fidelity modelling in the context of Multidisciplinary Design Optimization (MDO) on one side and making the use of high fidelity tools more efficient in the context of Multi-fidelity Design Approaches (MFDA) on the other.This thesis presents the …
-
Model Reduction Using Semidefinite Programming
In this thesis model reduction methods for linear time invariant systems are investigated. The reduced models are computed using semidefinite programming. Two ways of imposing the stability constraint are considered. However, both approaches add a positivity constraint to the program. The input to …
-
Real-time data assimilation in nonlinear dynamical systems
… Central to digital twins are physics-based low-order models and experimental data. On the one hand, low-order models are computationally cheap, but they may be quantitatively inaccurate and contain model errors. On the other hand, experimental data can be quantitatively accurate, but they …
-
Blade tonal noise reduction using tail articulation at high Reynolds number
… is carried out with a life scale stator model with hinged flapping tail designed to (i) operate in freestream velocities corresponding to Reynolds number in the range 75,000 < Re < 300,000 and (ii) operate at frequencies up to 30 Hz in order to investigate the range of Strouhal number 0.0 …
-
Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device
… is presented. Inaccuracies of the dynamic modeling of RUT based on Lloyd's low order model, which assumes constant hydrodynamic parameters irrespective of the frequency, are demonstrated by a series of high fidelity CFD simulations. These simulations are a systematic series of fully viscous …
-
Indirect noise in non-isentropic flows
Low emission aircraft engines burn in a lean regime, which makes the combustor susceptible to unsteady combustion. Along with improper mixing and air cooling, the unsteady combustion process gives rise to flow inhomogeneities. The acceleration of these inhomogeneities in the nozzle downstream of …
-
Modeling, simulation, and control of a polypyrrole-based conducting polymer actuator
A detailed model was developed for an ionic electro-active polymer (EAP) actuator. The electrical and chemical domains of the system were modeled using a simple electrical circuit. Ionic charge storage within the polymer was described using a linear reticulated model. This model improves upon the …
-
Low order models for hybrid gas bearings
A low order model was created to analyze a small scale gas bearing designed for the MIT microfabricated gas turbine engine. The journal has a diameter of 4.1 mm and is designed to spin at 2 million rpm. Due to microfabrication constraints, the bearing will have a very low length to diameter ratio …
-
Modeling, estimation and control for serial flexible robot arms
… manipulators, despite the potential benefits of lower costs, increased throughput and improved safety. Advancements in data processing capabilities, sensing capabilities and control theory during the past couple of decades can potentially solve the perceived problems with flexible serial …
-
Stethoscope acoustics
… to both the patient and the clinician. Existing models do not adequately address these interactions, forcing design choices to be made based on simple heuristics. The aims of this thesis are to provide a theoretical framework for understanding the acoustics of stethoscopes, propose a low order …
-
Hydrogen Enrichment Effects on Thermoacoustics of Turbulent Partially Premixed Flames
… and thermoacoustic instability in Gas Turbine Model Combustors (GTMC). A bimodal thermoacoustic instability where two different modes are excited are investigated using Large Eddy Simulations (LES) for a partially premixed swirl stabilised methane-air flame in a GTMC. Simulations are also …
-
Computational Modeling of Total Temperature Probes
… effect of leading edge curvature on near-field flow, and the influence of freestream Mach number and pressure on probe performance. Data were compared to experimental results from the literature, with freestream conditions of M=0.3-0.9, p_t=0.2-1 atm, T_t=300-1111.1 K. It is shown that 2D …
Page 1 of 2