Thermodynamics Commons^™

A Parametric Analysis Of A Turbofan Engine With An Auxiliary Bypass Combustion Chamber – The Turboaux Engine, Kaleab Fetahi

Mechanical & Aerospace Engineering Theses & Dissertations

A parametric study of a novel turbofan engine with an auxiliary combustion chamber, nicknamed the TurboAux engine is presented. The TurboAux engine is conceived as an extension of a low-bypass turbofan engine with an auxiliary bypass annular combustion chamber around the core stream. The study presented in this thesis is motivated by the need to facilitate clean secondary burning of fuel at temperatures higher than conventionally realized, from air exiting the low-pressure compressor. The parametric study starts by analyzing the turbojet engine and its performance with and without an afterburner segment attached. Following that, the conventional turbofan and its mixing …

Parametric Study Of Residual Stresses In Wire And Arc Additive Manufactured Parts, Hisham Khaled Jamil Abusalma

Mechanical & Aerospace Engineering Theses & Dissertations

Wire and Arc Additive Manufacturing (WAAM) is a cost-effective additive manufacturing process due to its capability to fabricate large metal parts with high deposition rate and low equipment cost. Although this method is gaining popularity in manufacturing industry, more research is needed to understand process parameters’ effects on residual stress (RS) distribution and part distortion. As such, a 3D thermo-elastic-plastic transient model was established in ABAQUS and employed to investigate the effect of process parameters such as the torch speed, the deposition power and the interlayer dwell time on RS distribution and distortion in WAAM part. The numerical model utilized …

Aerothermodynamic Analysis Of A Mars Sample Return Earth-Entry Vehicle, Daniel A. Boyd

Mechanical & Aerospace Engineering Theses & Dissertations

Because of the severe quarantine constraints that must be imposed on any returned extraterrestrial samples, the Mars sample return Earth-entry vehicle must remain intact through sample recovery. Vehicles returning on a Mars-Earth trajectory will attain velocities exceeding any that have been experienced by prior space exploration missions, with velocities approaching 14 km/s. Velocities as high as these will encounter significant heating during atmospheric re-entry to Earth.

The purpose of this study has been to systematically investigate the aerothermodynamic challenges that will result from a Mars sample return, Earth-entry vehicle design. The goal was to enable efficient estimation of maximum stagnation …

A Study Correlating Entropy Generation To Parameters Characterizing Thermal Comfort In A Conditioned Room, Sai Shrinivas Sreedharan

Mechanical & Aerospace Engineering Theses & Dissertations

Although significant advances have been made to analyze and study a room as an open thermodynamic system experiencing indoor airflow and heat exchanges with surroundings, studies incorporating entropy generation in the analysis have been sparse. This study focuses on correlating indoor thermal comfort with entropy generation, which hopefully will result in efficient utilization of energy supplied to the system. The problem that this thesis attempts to solve involves calculation of entropy production in conditioned space and its correlation to parameters that characterize thermal comfort. Thermal comfort in a conditioned space is governed by many thermal, mechanical and psychrometric parameters. The …

The Effectiveness Of Film Cooling In A Hypersonic Flowfield With Favorable Pressure Gradients, Julie A. Young

Mechanical & Aerospace Engineering Theses & Dissertations

The impetus of this technical document is to report results of aerothermodynamic cooling of a scramjet nozzle under favorable pressure gradients. The goals of film cooling are to protect the nozzle skin from the high enthalpy combustor flow, reduce regenerative cooling requirements, and decrease nozzle skin friction. A hypersonic nozzle configuration for which experimental data exists was selected as the basis of this numerical study. As a first step, the numerical results of film cooling along a flat plate are compared to previous literature to validate the numerical model. Subsequently, computations are performed to study the effects of varying the …

A Study Of The Thermodynamic And Heat Transfer Characteristics Of Two-Phase Two-Component Flow With Application To A Solar-Assisted Heat Pump, Walid A. Aziz

Mechanical & Aerospace Engineering Theses & Dissertations

Two-phase flow of single component refrigerants has been studied, theoretically and experimentally, for many CFCs, in many industrial applications, including the solar-assisted heat pump system. This study extends the thermodynamic and heat transfer analysis in the phase transition boiling region, to newly proposed refrigerant mixtures, which are candidates for replacing the classical CFCs for future HVAC applications. The goal of this study is to develop a methodology, to design the collector/evaporator tubes of a solar-assisted heat pump, using a binary refrigerant mixture as the working fluid. The method is implemented numerically as a computer algorithm. In order to do that, …

Effects Of Radiative Interactions In Molecular Gases Under Local And Nonlocal Thermodynamic Equilibrium Conditions, Manoj Kumar Jha

Mechanical & Aerospace Engineering Theses & Dissertations

Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions.

The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are …

Analysis Of Heat Pump Cycles Using Thermodynamic Equations Of State, Stephen C. Ericson

Mechanical & Aerospace Engineering Theses & Dissertations

In this study, thermal performance of heat pump cycles is analyzed by employing several equations of state. The analysis presented here is particularly useful for applications where refrigerant properties need to be calculated from a thermodynamic equation of state. Such a situation, for example, would arise during a long-term numerical simulation of a solar-assisted heat pump system. In these cases, the direct use of thermodynamic property tables of refrigerants would not be possible in a computational procedure. The approach of using equations of state to predict thermodynamic properties is also useful for applications where new refrigerants or blends of refrigerants …

Transient Simulation Of A Trombe Wall Passive Heating System Coupled To A Thermally Stratified Room, Ali Saleh Kheireddine

Mechanical & Aerospace Engineering Theses & Dissertations

Thermal performance of a Trombe-wall space heating system has been studied numerically for one-day and multiple-day periods. This study analyzes the system performance by simultaneously considering the coupled nature of the channel convection, wall heat conduction and transient room energy balance. A computer program has been written and implemented to assess the effects of system parameters, weather conditions and peak temperature control strategies on the system performance.

The system performance is influenced by such system parameters as the storage wall thickness, channel width and the temperature stratification in the room. Increasing the wall thickness decreases the temperature swings considerably, but …

Thermal Compatibility Analysis Of The Passive Damping Treatment Proposed For The Space Shuttle Remote Manipulator System (Srms), Mahesh Chowdhary

Mechanical & Aerospace Engineering Theses & Dissertations

The NASA Space Shuttle Remote Manipulator System (SRMS), due to its long reach and light weight construction has significant structural flexibility. Thus any routine use of SRMS often results in large amplitude oscillations with long settling time. A passive damping technique utilizing a constrained viscoelastic layer damping treatment has been proposed to augment the active control of these oscillations in order to enhance the system stability and the end effector positional accuracy. This thesis concerns with the thermal compatibility analysis of the proposed damping treatment. The necessity for thermal compatibility analysis arises from the fact that acceptable damping performance of …

Evaluation Of Equilibrium Turbulence For A Hypersonic Boundary Layer At Nonadiabatic Wall Conditions, Cindy W. Albertson

Mechanical & Aerospace Engineering Theses & Dissertations

This paper presents an experimental study to characterize the compressible turbulent boundary layer produced along a flat plate in the NASA Langley 8-Foot High Temperature Tunnel and determine the test conditions necessary to achieve equilibrium turbulence. In addition, the present study extends the data base for equilibrium compressible turbulent boundary layers over quasi-isothermal walls which are far from the adiabatic wall temperature. The measurements consist of pilot pressure, static pressure, and total temperature distributions in the boundary layer. A flat plate measuring 9.7 feet long and 4.3, feet wide was used for the study to provide a naturally turbulent boundary …