The Development Of Shock Tube And Study On Ignition Delay Characteristics Of RP-3 Kerosene

The deterioration of combustion chamber performance due to low pressure combustion is an important factor limiting the increase of scramjet lift limit.Studying the basic characteristics of ignition and combustion of fuel in low pressure environment and revealing the combustion mechanism of fuel under low pressure condition are of great significance for improving the flame stability of combustor under extreme conditions and increasing the working lift of ramjet engine.The measurement of kerosene ignition delay plays a key role in simplifying the chemical kinetic mechanism of fuel,establishing and validating the reaction kinetic model.Shock tube can obtain a wide range of experimental temperature and pressure by changing the Mach number of incident shock wave.It is an effective experimental tool for studying the ignition delay characteristics of fuel.The main contents of this paper are as follows:（1）The chemical shock tube was designed and developed to study the ignition delay characteristics of RP-3 kerosene at low pressure.The shock tube experimental equipment consists of shock tube body,gas distribution system,pressure signal monitoring system and optical measurement system.The low-pressure section was heated at 383 K.The gas phase concentration of RP-3 kerosene was determined by the pressure and adsorption curve of RP-3 kerosene at 383 K.The optical window is located 20 mm near the end cover of the low pressure section,which reduces the influence of combustion wave on the experimental measurement and avoids the phenomenon of signal tailing.（2）The ignition delay time of RP-3 kerosene/O₂/N₂ was determined by shock tube based on the characteristic emission spectrum of OH radical at 306.5 nm and the pressure signal near the end cover of the low pressure section.The ignition delay time of RP-3 kerosene/O₂/N₂ mixture was measured at pressure of 0.01 MPa,0.03 MPa,0.05 MPa and 0.01 MPa,temperature of 1113K-1600 K,equivalent ratio of 0.5,1 and 1.The effects of temperature,pressure and equivalence ratio on ignition delay of RP-3 kerosene were investigated.It is found that the ignition delay time can be shortened with the increase of temperature,pressure and the decrease of equivalent ratio.The dependence relation of the ignition delay time of RP-3 kerosene with temperature,pressure,equivalent ratio and other parameters was obtained by least squares fitting as follows:（?）（3）The influence of CO₂ on the ignition delay characteristics of RP-3 kerosene was studied.Firstly,the ignition delay time of kerosene was measured when the ratio of partial pressure of CO₂ to partial pressure of RP-3 kerosene/O₂/N₂ mixture was 0%,10% and 20%.Subsequently,the ignition delay time of kerosene at different equivalence ratios was measured by replacing part of diluted gas N₂ with CO₂.The results indicated that when the equivalence ratio is 1,with the ratio of CO₂ partial pressure to RP-3 kerosene/O₂/N₂ mixture partial pressure increasing from 0% to 10% and 20%,the ignition delay time of RP-3 kerosene mixture increases.With the decrease of temperature,the effect of CO₂ on ignition delay of RP-3 kerosene mixture increases.The sensitivity of ignition delay time to CO₂ content increases as the equivalent ratio increases from 0.5 to 1.5...