An experimental investigation of supersonic combustion of cracked JP-10

In this paper, a novel two-stage hydrocarbon fuel heating and delivery system was used to more accurately simulate the state of fuel in the cooling channel of the regenerative cooling engine. Different cracking degrees (9-23%) experiments of JP-10 were conducted by using the new heating system, and cracked products were sampled and analyzed. The ignition delay time of high cracking degree product is shorter than that of low cracking degree product. The laminar flame speed of JP-10 and low cracking degree products are similar, the laminar flame speed of high cracking degree products is 32% faster than that of JP-10 when the equivalence ratio is 1.0, and the laminar flame speed of surrogate gas fuel is two times faster than that of JP-10. The supersonic combustion experiments of JP-10 with different cracking degrees and equivalence ratios were also employed at Mach number 3.0 of the isolator entrance, with total temperature-1550 K, total pressure-1.5 MPa, as well as at Mach number 2.5 of the isolator entrance, with total temperature-1250 K, total pressure-0.78 MPa, respectively. The static pressure along the axis of combustor was measured, while the velocity and temperature of the airflow at the exit of combustor were also measured by the tunable diode laser absorption spectroscopy (TDLAS). The distributions of airflow velocity, total temperature and static temperature along the combustor with different conditions were analyzed through a one-dimensional analysis method. The deviations of velocity and temperature of the airflow are less than-4% and-5% for Mach number 3.0, and less than 9% and 4% for Mach number 2.5, which indicates the calculations are in accordance with the TDLAS detections to some extent at Mach 3.0. Specially, supersonic combustion of JP-10 with different cracking degree at the same fuel tem-perature and equivalence ratio were obtained, which benefits studying the influence of different cracking degrees fuel on supersonic combustion characteristics. Furthermore, the experimental data will be helpful for validating the simulation of supersonic combustion.