Shock tube study of the effect of unsymmetric dimethyl hydrazine on the ignition characteristics of hydrogen-air mixtures

Ignition delays of lean, stoichiometric, and rich mixtures of hydrogen air over a temperature range 800-1400°K and a pressure of 2.5 atm were experimentally determined using a shock tube. Small quantities of unsymmetric Dimethyl Hydrazine (UDMH) were added to the above mixtures and their delay periods for the same temperatures and pressure as mentioned earlier were determined. Ignition was identified by the pressure rise as well as visible light emission using piezoelectric pressure pickups and photomultipliers respectively. The delay periods of lean, stoichiometric, and rich mixtures of hydrogen air are found to decrease with the addition of small quantities (less than 1%) of UDMH. When the concentration of UDMH in the mixture exceeds 3%, it is found that the delay periods tend to be longer than those obtained when no UDMH was present. A probable reaseon for these phenomena is offered. © 1973.