Progress in conventional rocket engine technologies, based on constant pressure combustion, has plateaued in the past few decades. Rotating detonation engines (RDEs) are of particular interest to the rocket propulsion community as pressure gain combustion may provide improvements to specific impulse relevant to booster applications. Despite recent significant investment in RDE technologies, little research has been conducted to date into the effect of nozzle design on rocket application RDEs. Proper nozzle design is critical to capturing the thrust potential of the transient pressure ratios produced by the thrust chamber. A computational fluid dynamics study was conducted based on hotfire conditions tested in the Purdue V1.3 RDE campaign. Three geometries were investigated: nozzleless/blunt body, internal-external expansion (IE-) aerospike, and flared aerospike. The computational study found the RDE's dynamic exhaust plume enhances the ejection physics beyond that of a typical high pressure device. For the nozzleless geometry, the base pressure was drawn down below constant pressure estimates, increasing the base drag on the engine. For the aerospike geometries, the occurrance of flow separation on the plug was delayed, which has ramifications on nozzle design for operation at a range of pressure altitudes. The flared aerospike design, which has the ability to achieve much higher area ratios, was shown to have potential performance benefits over the limited IE-aerospike geometry. A new test campaign with the Purdue RDE V1.4 was designed with instrumentation to capture static pressures on the nozzleless and aerospike surfaces. These results were used to validate the results from the computational study. The computational and experimental studies were used to identify new flow physics associated with a rocket RDE important to future nozzle design work. Future computational work is necessary to explore the effect of different parameters on the nozzle performance. More testing, including with an altitude simulation chamber, would help quantify the possible benefit of new aerospike nozzle designs, including the flared aerospike geometry.

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An important part of automobile safety is the braking system. Disc brakes have been widely used in automobiles for sped retardation for over 30 years. During that time, they have developed from a simple disc to a complex disc with channels, vanes, holes and grooves. The stopping capability of disc brakes is affected by the rate at which heat is dissipated by forced convection and the thermal capacity of the rotor. Catastrophic failure of brake rotors can occur during rapid increases or decreases in rotor temperature where regions of high temperature gradients result in high thermal strains. There is little information in the public domain regarding the relative merits of different disc brake rotor geometries, particularly in terms of airflow patterns, heat transfer rates, and internal thermal gradients. The aim of this research project was to investigate how geometrical variations affect the thermal performance of bi-directional disc brake rotors, particularly for high performance applications. Dynamometer testing showed that respectable increases in braking performance are achievable with relatively simple machining modifications. Tuft and smoke visualization techniques provided a preliminary understanding of the airflow in the passages of three distinct bi-directional rotor designs. Particle Image Velocimetry was used for detailed flow measurements which supported the numerical simulations. Computational Fluid Dynamics was used to predict the airflow and heat transfer associated with eight bi-directional brake rotor designs. The results show that 'pillared' passage designs can achieve higher heat transfer rates than traditional straight radial vane designs and that the heat loss from pillared rotors is generally more uniform than from vaned rotors. Subsequent conjugate heat transfer simulations found that temperature gradients inside pillared rotors are typically lower than inside vaned rotors. Thus failure rates due to excessive thermal strain are expected to be lower for pillared rotors. It was shown that rotor selection based solely on heat transfer rates is inappropriate and different passage designs are suited to different applications. The findings of this research will directly benefit local disc brake manufacturers, who do not have resources to conduct thorough studies comparing the thermal characteristics of different brake rotor designs.

Thesis (S.M.)--Joint Program in Physical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences and the Woods Hole Oceanographic Institution), 2002. / Includes bibliographical references (p. 75-77).

In this thesis, large-eddy simulation has been performed to investigate a heated plane channel flow subjected to streamwise system rotations. A variety of rotation numbers ranging from Roτ = 0 to 15 have been tested in conjunction with two fixed low Reynolds numbers Reτ = 150 and 300. The fundamental characteristics of the resolved velocity and temperature fields in terms of their mean and root-mean-square (RMS) values are investigated. Advanced physical features in terms of the transport of turbulent stresses, turbulent kinetic energy (TKE), heat fluxes and forward and backward scatter of local kinetic energy (KE) fluxes between the resolved and subgrid scales are also studied. Numerical simulations were performed using the conventional dynamic model (DM) and an advanced dynamic nonlinear model (DNM) for closure of the filter momentum equation, and an advanced dynamic full linear tensor thermal diffusivity model (DFLTDM) for closure of the filtered thermal energy equation.

No description available.

In this thesis, large-eddy simulation has been performed to investigate a heated plane channel flow subjected to streamwise system rotations. A variety of rotation numbers ranging from Roτ = 0 to 15 have been tested in conjunction with two fixed low Reynolds numbers Reτ = 150 and 300. The fundamental characteristics of the resolved velocity and temperature fields in terms of their mean and root-mean-square (RMS) values are investigated. Advanced physical features in terms of the transport of turbulent stresses, turbulent kinetic energy (TKE), heat fluxes and forward and backward scatter of local kinetic energy (KE) fluxes between the resolved and subgrid scales are also studied. Numerical simulations were performed using the conventional dynamic model (DM) and an advanced dynamic nonlinear model (DNM) for closure of the filter momentum equation, and an advanced dynamic full linear tensor thermal diffusivity model (DFLTDM) for closure of the filtered thermal energy equation.

Thesis (Ph. D.)--Massachusetts Institute of Technology, 1966. / Includes bibliographical references (leaves 153).