Experimental investigations on effects of wall-temperature on performance of a pulse detonation rocket engine

• Long-duration experiments were conducted to study effects of wall-temperature.
• It was observed that wall-temperature had a positive effect on the DDT process.
• Wall-temperature was also found to have a relationship with detonation pressure.
• Extraordinary high wall-temperature would cause pre-ignition of fresh reactants.

To study the effects of wall-temperature on performance of a pulse detonation rocket engine (PDRE), long-duration experiments were conducted. An internally grooved semi-circle spiral, instead of traditional Shchelkin spiral, was utilized to facilitate the deflagration to detonation transition (DDT) process and prolong run time in the present study. Four pressure transducers and a type K thermocouple were employed to collect data during the experiments. Experiments were carried out at three different operating frequencies, such as 10 Hz, 20 Hz and 30 Hz, until unstable operation happened. The results showed that wall-temperature increased faster at higher operating frequency. It was observed that DDT time and DDT distance both decreased with the increase of wall-temperature, and detonation pressure increased sharply with wall-temperature first and then decreased slowly when wall-temperature exceeded a certain value. Both of them were believed to be due to the impact of hot-wall on fuel vaporization and reactant temperature. Unreasonably high wall-temperature was found to cause pre-ignition of fuel–oxidizer mixture, and this was why unstable operation of the PDRE happened after long-duration runs. In addition, effects of wall-temperature on specific impulse was also discussed.