Finally, these strategies have been more » used to measure low-temperature n-heptane ignition delay times.
Spectroscopically based temperature measurements in non-reactive mixtures have confirmed that temperature and pressure conditions remain constant throughout the length of these long test duration trials.
HELIO GAS RJ DRIVER
Using this staged driver gas filling, in addition to the other techniques listed above, post-reflected shock test times of up to 0.102 s (102 ms) at 524 K and 1.6 atm have been obtained. This filling scheme involves firstly mixing a tailored helium–nitrogen mixture in the driver section as in conventional driver filling and, secondly, backfilling a low-speed-of-sound gas such as nitrogen or carbon dioxide from a port close to the end cap of the driver section. Experiments indicate that this staged filling strategy increases available test time by roughly 20 % relative to single-stage filling of tailored driver gas mixtures, while simultaneously reducing the helium required per shock by up to 85 %. Here, we detail these techniques, including discussion on the most recent strategy, staged driver gas filling. Several techniques have been developed for obtaining long, constant-pressure test times in reflected shock wave experiments in a shock tube, including the use of driver inserts, driver gas tailoring, helium gas diaphragm interfaces, driver extensions, and staged driver gas filling.
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