Mechanical Engineering Commons^™

Single-Phase Turbulent Enthalpy Transport, Bradley J. Shields

Masters Theses

Vapor generation is central to the flow dynamics within fuel injector nozzles. Because the degree of atomization affects engine emissions and spray characteristics, quantification of phase change within diesel fuel injectors is a topic of design interest. Within the nozzle, the large pressure gradient between the upstream and downstream plena induce large velocities, creating separation and further pressure drop at the inlet corner. When local pressure in the throat drops below the fluid vapor pressure, phase change can occur with sufficient time. At the elevated temperatures present in diesel engines, this process can be dependent upon the degree of superheat, …

Measurement And Verification - Retro-Commissioning Of A Leed Gold Rated Building Through Means Of An Energy Model: Are Aggressive Energy Simulation Models Reliable?, Justin M. Marmaras

Masters Theses

During the construction of the new 3 story, 25,000+ square foot police station, a decision was made to participate in the LEED program to ensure the building had low operating costs, reduced emissions, conserved water and overall energy. The design of the building includes a primary-secondary ground source heat pump (GSHP) loop, a Dedicated Outside Air System (DOAS) with Energy Recovery Ventilation (ERV) wheel, all controlled by CO2 monitoring through Demand Control Ventilation (DCV) to supply heat pumps located in each space; all monitored by a Building Automation System (BAS).

The building’s future energy performance was predicted through an energy …

Design And Fabrication Of A Low-Cost Turbine Engine Component Testbed (Tect), Joshua A. Hartman

Masters Theses

With gas turbine engine testing becoming very expensive because of the increasing complexity involved with the engine, engine subsystems, and test support systems, a low-cost Turbine Engine Component Testbed (TECT) is proposed. This engine build is given the designation J1-H-02. In the present study, a small augmented gas turbine engine (GTE) is constructed. The TECT engine is built with modularity as a key design consideration to allow for flame-tube patterns and augmentor sections to be changed quickly for combustion experiments that have gained impetus due to combustion anomalies/instabilities inherent with future military engine augmentors. This testbed allows for an effective …

Formulation And Experimental Verification Of Alternate Calibration Techniques Of The Temperature Dependent Response Of Phosphor Fluorescence, Kelsey Michele Winstead

Masters Theses

The overall goal of this work is to provide an alternative approach to the thermographic phosphor (TP) time constant calibration method for temperature recovery. In this work two techniques are proposed that retain the pulsed source input used in the standard TP time constant calibration approach but reinterpret the phosphor response taken a fixed distance such that the single-exponential decay assumption is removed. The methods do not require knowledge of key parameters prior to data processing, nor do they involve complicated numerical schemes that attempt to fit data in the low signal-to-noise region of the phosphor response. The approaches do …

Neutron Imaging Of Lithium (Li) Coolants Inside High Temperature Niobium (Nb) Heat Pipes, Brad Harrison Hight

Masters Theses

Lithium (Li) behavior inside a high temperature Nb-Li leading edge heat pipe was successfully imaged under induction heating operation via neutron imaging. Startup and cool-down operations gave visual confirmation of bulk Li movement using both gravity assisted and inverted operating orientations. The pipe was imaged during an operation cycle from ambient conditions, heated to a steady state temperature of 908.8 ⁰C, and allowed to cool below 200^°C. The experiment was performed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, and at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee.

Tomographic images …

Thermal Response Characterization And Low Fluid Velocity Measurements Using Specialized In-Situ Thermocouples Via The Loop Current Step Response Method, Alexander Hashem Hashemian

Masters Theses

In this study, a specialized balanced-leads thermocouple was developed to perform in-situ thermal response characterization via the LCSR test method. Thermal response characterization of installed thermocouples is essential in order to obtain accurate positional temperature data in rapid transient applications. An analytical model is presented that fully describes the thermocouple system based on a first-principles approach to the heat transfer physics of the sensor. In conjunction with the LCSR test, the full model presented yields quantifiable characterization parameters useful for determining accurate positional temperature data. It is necessary to employ a balanced-leads thermocouple for this experimental procedure in order to …

Simulation Of An Intake Manifold Pre-Heater For Cold Diesel Engine Startup, Patrick K. Kreun

Masters Theses

Ensuring consistent, reliable diesel engine startups in cold temperatures is of utmost importance in a number of applications. Under extreme temperatures, the use of glow plugs is complemented by intake manifold heaters. In these, the energy released from combustion increases the intake air temperature before the air enters the main combustion chamber. Since the process also alters the stoichiometry of the fuel-air mixture at the intake ports, the preheater operation must be optimized in order to guarantee successful and reliable in-cylinder combustion during engine startups. This paper describes the development of an intake manifold model incorporating an air pre-heater for …

Analytical Performance Evaluation Of Thermoelectric Modules Using Effective Material Properties, Sean Lwe Leslie Weera

Masters Theses

Designers often face the predicament of non-standardized forms of performance data provided by thermoelectric module manufacturers. Other than experimental means the only method to evaluate the performance of a product would be through analytical modeling using material properties that are usually undisclosed and unknown. This work studies the theoretical approach of obtaining such material properties using the maximum operating parameters reported by the manufacturers. These values are then analytically employed to evaluate the performances of these thermoelectric modules. Experimental means are also devised and carried out on these test samples to validate the integrity of the results. Three-way comparisons between …