INVESTIGATION OF INTRAOCULAR PRESSURE AS A PREDICTOR OF TRAUMATIC EYE INJURIES

Eye injuries are a large societal problem in both the military and civilian sectors. Eye injury rates are increasing in recent military conflicts, and there are over 1.9 million eye injuries in the United States civilian sector annually. In order to develop a better understanding of eye injury risk, several previous studies have developed eye injury criteria based on projectile characteristics. While these injury criteria have been used to estimate eye injury potential of impact scenarios, they require that the mass, size and velocity of the projectile are known. It is desirable to develop a method to assess the severity of an eye impact in environments where it would be difficult or impossible to determine these projectile characteristics. The current study presents a measurement technique for monitoring intraocular pressure of the eye under impactloading. Through experimental tests with a custom pressure chamber, a subminiature pressure transducer was validated to be thermally stable and suitable for testing in an impact environment.Once validated, the transducer was utilized intraocularly, inserted through the optic nerve, to measure the pressure of the eye during blunt-projectile impacts. A total of 150 impact tests were performed using projectiles ranging from 3.2 mm to 17.5 mm in diameter. Investigation of the relationship between projectile energy and intraocular pressure lead to the identification of at least two distinct trends. Intraocular pressure and normalized energy measurements indicated a different response for penetrating-type globe rupture injuries with smaller diameter (d < 1 cm)projectiles, and blunt-type globe rupture injuries with larger diameter (d > 1 cm) projectiles. Furthermore, regression analysis indicates that relationships exist between intraocular pressureand projectile energy that may allow quantification of eye injury risk based on pressure data, and also that intraocular pressure measurements of impact may lead to a better understanding of thetransition between penetrating and blunt globe rupture injury mechanisms.

Revision of a Liquid Fuel Airblast Atomizer and Installation of a Laser Extinction System for Measurement of Soot Produced During Liquid Fuel Combustion

Studying liquid fuel combustion is necessary to better design combustion systems. Through more efficient combustors and alternative fuels, it is possible to reduce greenhouse gases and harmful emissions. In particular, coal-derived and Fischer-Tropsch liquid fuels are of interest because, in addition to producing fewer emissions, they have the potential to drastically reduce the United States' dependence on foreign oil. Major academic research institutions like the Pennsylvania State University perform cutting-edge research in many areas of combustion. The Combustion Research Laboratory (CRL) at Bucknell University is striving to develop the necessary equipment to be capable of both independent and collaborative research efforts with Penn State and in the process, advance the CRL to the forefront of combustion studies. The focus of this thesis is to advance the capabilities of the Combustion Research Lab at Bucknell. Specifically, this was accomplished through a revision to a previously designed liquid fuel injector, and through the design and installation of a laser extinction system for the measurement of soot produced during combustion. The previous liquid fuel injector with a 0.005" hole did not behave as expected. Through spray testing the 0.005" injector with water, it was determined that experimental errors were made in the original pressure testing of the injector. Using data from the spray testing experiment, new theoretical hole sizes of the injector were calculated. New injectors with 0.007" and 0.0085" orifices were fabricated and subsequently tested to qualitatively validate their behavior. The injectors were installed in the combustion rig in the CRL and hot-fire tested with liquid heptane. The 0.0085" injector yielded a manageable fuel pressure and produced a broad flame. A laser extinction system was designed and installed in the CRL. This involved the fabrication of a number of custom-designed parts and the specification of laser extinction equipment for purchase. A standard operating procedure for the laser extinction system was developed to provide a consistent, safe method for measuring soot formation during combustion.