Vortragende/r: Prof. Joseph E. Shepherd
Institut: California Institute of Technology, Pasadena
Ort: PTB Braunschweig, Hörsaal
An overview of the recent research studies in the Explosion Dynamics Laboratory at Caltech will be presented. The research themes in our laboratory are oriented toward the characterization of combustion processes and structural effects that are relevant to determining the risk and severity of accidental explosions. Results will be presented on studies of three problems: electrostatic spark ignition, thermal ignition, and structural response (elastic and plastic) of tube to internal explosions.
The studies of electrostatic ignition have focused on developing experimental methods to reliably create low energy (< 1 mJ), short-duration (10 ns) discharges that are characteristic of accidental electrostatic ignition. Ignition thresholds are treated with statistical methods as an alternative to the classical view of minimum ignition energy. The studies of thermal ignition have examined the both the classical problem of autoignition in a slowly-heated vessel and ignition due to localized hot surfaces. Two new effects have been identified: a sharp transition between benign reaction consumption and rapid explosion as a function of heating rate and mixture parameters; a unique cyclic mode of combustion in a premixed mixture surrounding a thermal igniter. The studies of structural response have examined the elastic and plastic deformations of piping systems due to deflagrations, detonations, and transition from deflagration to detonation.