Experimental Investigation of a Cylindrical Air-Breathing Continuous Rotating Detonation Engine with Different Nozzle Throat Diameters

Abstract

A continuous detonation engine with various exhaust nozzles, analogous to typical scramjet cavity combustors with variable rear-wall heights, was adopted to perform a succession of cylindrical air-breathing continuous rotating detonation experiments fueled by a non-premixed ethylene/air mixture. The results show that the detonation combustion was observed to self-sustain in the combustor through simultaneous high-speed imaging covering the combustor and isolator. A long test, lasting more than three seconds, was performed in this unique configuration, indicating that the cylindrical isolator–combustor engine exhibits potential for practical applications. Three distinct combustion modes were revealed with varied equivalent ratios (hybrid mode, sawtooth wave mode, and deflagration mode). The diameter of the nozzle throat was critical in the formation of rotating detonation waves. When the nozzle throat diameter was larger than the specific value, the detonation wave could not form and self-sustain. The upstream boundary of the shock train was supposed to be close to the isolator entrance in conditions of a high equivalence ratio and small nozzle throat diameter. In addition, it was verified that periodic high-frequency pressure oscillation could cause substantial impacts on the incoming flow as compared with the steady deflagration with the same combustor pressure.

Numerical Investigation on Detonation Initiation and Propagation with a Symmetric-Jet in Supersonic Combustible Gas

“…The penetration height of jet formula is expressed as follows [44,45]: H p = 2.713D 0.719 j J 0.273 (6) When the jet diameter increases from 2.5 mm to 4.5 mm, the momentum flux ratio J remains unchanged, whereas the jet penetration increases from 4.5028 to 6.8710. This means the strength of the bow shock increases accordingly.…”

“…To meet the higher requirements for propulsion performance of future hypersonic vehicles, a concept of scramjet based on detonation combustion was proposed [4]. The new type of detonation combustion power device is gradually becoming a potential power method for improving the thrust performance of hypersonic vehicles owing to its higher thermal cycle efficiency and heat release rate [5][6][7]. It should be noted that the reliable ignition and stable propagation of detonation waves in a supersonic flow field are the core problems that need to be solved urgently [8].…”

Cyclic Ablation Properties of C/SiC-ZrC Composites

“…There have been many studies on the mechanism of single ablation of C/SiC composites, but many high-temperature environments are not continuous. For example, the high-temperature environment of RDE is periodic [27][28][29]. Therefore, studying cyclic ablation can better reveal the ablation performance of materials under this working condition.…”

Experimental investigation on air-breathing continuous rotating detonation engine in the cavity-based combustor

“…The self-sustained propagation of the detonation wave is achieved in both the design condition Ma=2 and the non-design condition Ma=1.5. A series of experiments on empty-barrel aspirated detonation engines with tail nozzles of different sizes were carried out by Wang et al [11], which using a non-premixed ethylene/air mixture as fuel. The results show that the formation of the rotating detonation wave mainly depends on the size of the tail nozzle, and the size of the nozzle throat will lead to the failure of the formation of the detonation wave.…”