Investigation of Ignition Delay for Low Molecular Weight Hydrocarbon Fuel by Using Shock Tube in Reflected Shock Mode

Abstract

Shock tube facility in the Propulsion and High Enthalpy laboratory, Aerospace Engineering Department, has been extensively used to study the ignition characteristics of fuels by measuring the ignition delay times for various hydrocarbon fuels at high temperatures. Initially a systematic method has been followed to calibrate the shock tube for ignition delay time measurements by measuring the delay times of C2H6 – O2 gas mixture diluted with argon. The results show good agreement with earlier reported works of Ethane ignition. Ignition times of low molecular weight liquefied petroleum gas, a fuel used in many industrial and household applications has been studied in the temperature range of 1250–1880 K and in the pressure range of 6–11 atm at equivalence ratios (Φ = 0.5 & 1). The ignition delay was measured in the reflected shock region by recording the ignitioninduced pressure rise and emission from CH radical simultaneously. From the present study it is noted that the ignition delay time for liquefied petroleum gas reduces with increase in temperature and its activation energy lies in the range of 40 kcal/mol.