The protection of aircraft against shoulder fired heat seeking missiles is of growing concern in the aviation community. This thesis presents a simple method for shielding the infrared signature of a jet engine from heat seeking missiles. The research efforts investigated two approaches to shield the thermal signature of the Noel Penny Type 401 turbojet at the Texas A&M University Propulsion Lab Test Cell. First, liquid nitrogen was injected through a manifold at a flow rate equivalent to the flow rate of exhaust gases, producing a small temperature reduction in the exhaust but no infrared shielding. Second, water was injected at a flow rate of 13% of the flow of exhaust gases, producing a greater temperature reduction and some shielding. Water was then injected through a manifold at a flow rate of 118% of the flow rate of exhaust gases, producing a substantial reduction in temperature and complete shielding of the infrared signature. Additionally, numerical simulations were performed using FLUENT to support these experiments. Results are presented in the form of thermocouple data and thermal images from the experiments, and in the form of temperature contours and streamtraces from the simulations.

The protection of aircraft against shoulder fired heat seeking missiles is of growing concern in the aviation community. This thesis presents a simple method for shielding the infrared signature of a jet engine from heat seeking missiles. The research efforts investigated two approaches to shield the thermal signature of the Noel Penny Type 401 turbojet at the Texas A&M University Propulsion Lab Test Cell. First, liquid nitrogen was injected through a manifold at a flow rate equivalent to the flow rate of exhaust gases, producing a small temperature reduction in the exhaust but no infrared shielding. Second, water was injected at a flow rate of 13% of the flow of exhaust gases, producing a greater temperature reduction and some shielding. Water was then injected through a manifold at a flow rate of 118% of the flow rate of exhaust gases, producing a substantial reduction in temperature and complete shielding of the infrared signature. Additionally, numerical simulations were performed using FLUENT to support these experiments. Results are presented in the form of thermocouple data and thermal images from the experiments, and in the form of temperature contours and streamtraces from the simulations.

<div> <div> <div> <p>Transient liquid phase sintering (TLPS) technologies are potential low-temperature solders for sustainable replacements of lead-based solders and high-temperature lead-free solders. Compared to solid-state sintering and lead-free solders, TLPS uses lower temperatures and is, thus, suitable for assembling temperature-sensitive components. TLPS is a non- equilibrium process and determining the kinetics is critical to the estimation of processing times needed for good joining. The tin-indium (Sn-In) system with a eutectic temperature of 119°C is being considered as the basis for a TLPS system when combined with tin. Most models of TLPS include interdiffusion, dissolution, isothermal solidification, and homogenization and are based on simple binary alloys without intermediate phases. The Sn-In system has two intermediate phases and thus the reaction kinetics require additional terms in the modeling. Differential Scanning Calorimetry (DSC) has been used to measure the response of Sn-In alloys during the transient liquid phase reaction. Preparation of tin indium alloys for microstructural analysis is challenging due to their very low hardness. This study uses freeze-fracturing of the tin indium alloys to obtain sections for microstructural analysis. The combination of DSC and microstructure analysis provides information on the reaction kinetics. It was observed that the solid/liquid reaction does not proceed as quickly as desired, that is, substantial liquid remains after annealing even though the overall composition is in the single-phase region in the phase diagram. </p> </div> </div> </div>