Cold-flow experimental studies on performance of the tile-shaped aerospike nozzles

Aerospike-nozzle engines are considered as a candidate for the next generation of propulsion systems for reusable launch vehicles because this nozzle offers a continuous altitude adaptation up to its design pressure ratio. Comparing with annular and linear aerospike nozzles, the the-shaped aerospike nozzle with the axisymmetric thrust cell and the concave plug improves a better plug flow, also has high performance and good altitude compensation ability. To know more characteristics of the-shaped aerospike nozzles and to get more experimental data that can be used for the validation of numerical simulation and analysis, cold-flow experimental studies on the the-shaped aerospike nozzles were carried out using highly pressurized air as propellant. The aero ratio of internal nozzle of thrust cell is 5.81 and the total aero ratios of the aerospike models are 24.36, 29.43, 33.88 and 37.58. Design parameters and structure photographs of the experimental engine and the test apparatus were introduced. Chamber pressure, thrust and ambient pressure were acquired and data analyses were also provided. Good altitude compensation capacities and high efficiencies were obtained in the tests. The maximum nozzle thrust efficiency of the the-shaped nozzles tested here is 96%. The effects of variation in the amount of base bleed and the inclination angle on performance were examined in the tests. The bleed can increase the base pressure, the effect of bleed on the performance is within 1%-2% and a little bleed is effective to improve the performance. The base pressure increases when the inclination angle becomes bigger and there is an optimum angle for the optimum performance. The effects of base sidewalls on base pressure were also analyzed. The results indicate that whether the base pressure changes with the ambient backpressure or not depends on the base region is working at open or closed wake condition. The the-shaped aerospike nozzle has good altitude compensation, and should be attractive to study further.