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K: Kurzzeitphysik

K 1: Short time-scale dynamics and diagnostics

K 1.8: Vortrag

Montag, 2. April 2001, 18:20–18:35, EB107

Transient Temperature Measurement in Detonation Gases — •Volker Aust — Fraunhofer EMI, Freiburg i. Br.

This presentation deals with transient temperature measurements in high-speed detonation gases formed by the detonation of 60 g of high explosive charges, either PETN or Composition B, in an open chamber. The transient optical method used is based on the recording of visible or infrared radiation (1 - 5 mikrometers) emitted by the expanding detonation cloud. Since the evaluation of gas temperature from the spectral emission presumes blackbody conditions, at first the absorptance of the detonation gases was controlled by probing it with laser beams of high intensity. The measured high absorptance of the gases (transmittance less than 10E-6) justifies the above assumption. Here gas temperatures are derived from emission recordings at wavelengths of 514 nm and 632 nm. The temperature-time plots represent the arrival of the fast outer blast wave with peak temperatures above 3000 K, followed by the gas cloud with temperatures below 2500 K that indicate the cooling of the gases during expansion. In addition to the temperature curves, examples of spectra measured in the visible and IR region are presented. Also, the experimental setup and measurement method are explained to some detail.