Experimental performance evaluation of 3N-class pulse detonation thruster using liquid purge method

A pulse detonation thruster (PD thruster) is a kind of reaction control system for controlling the attitude of a spacecraft using high-precision short-pulse thrust by intermittent detonation wave. Using a liquid-purge method proposed by Matsuoka et al. (Combustion Science and Technology, Vol. 187, No. 5, pp. 747-764, 2015), a 3N-calss PD thruster demonstrator was constructed in which the total length of combustor was 491.5 mm, inner diameter was 10 mm, and the total weight was 1241 g. In the liquid-purge method (LIP method) residual burned gas in combustor is cooled and purged by the latent heat of injected liquid droplet. This purge technique can realize a pulse detonation cycle using only fuel and oxidizer. Therefore it is possible to operate the pulse detonation cycle at high frequency without a purge process and a purge gas system. The thrust measurement experiment using the PD thruster at an operation frequency of 50 Hz was carried out and the thruster performance was evaluated. In a condition that injection duration was 6 ms, a time-averaged thrust of 2.3 ± 0.1 N, a propellant-based specific impulse of 113 ± 11 s, and a thrust-to-engine weight ratio of 0.19 were obtained. This thrust-to-engine weight ratio was the same level of a conventional 1N-calss monopropellant thruster. Furthermore the impulse in each pulse detonation cycle was 20.8 ± 2.6 mNs and the impulse repeatability was ± 12.3%. Moreover, the centroid time that is defined as the delay from the input signal to the thrust was 7.9 ± 0.1 ms. Therefore it was confirmed that a PD thruster has high thruster performance, namely, the high impulse repeatability and the high thrust response.