Multitube Thrust Chamber Dynamics

In addition to the study of single-tube PDE system dynamics, much effort was expended to investigate the intricate combustion and gasdynamic processes in multitube thrust chambers. 

Stable cyclic operation is reached at the fifth cycle. The cycle-averaged specific impulse and specific thrust obtained are 3543 s and 896 m/s, respectively. They are about 5% higher than those achieved by the single-tube PDE, demon- 

In another configuration, the length of the detonation tube decreases to 45 cm, leaving a free volume of 15 cm long between the detonation tubes and the nozzle. The flowfield exhibits a structure similar to the case without free volume. The cycle-averaged specific impulse and specific thrust are 3411 s and 

Inclusion of a free volume further reduces the degree of unsteadiness, although the system performance may not necessarily increase. 

It should be noted that there may exist lateral thrust in the vertical direction for multitube PDEs due to their unsymmetric operations. The present triple-tube PDE may produce a degree of unsteadiness of the engine operation. In the triple-tube cases, maximum lateral thrust of 1000 N per 1 kg/s air mass flow rate, thereby causing unnecessary vibration of the vehicle. This undesired effect can be harnessed by introducing the concept of tube pair. 

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The research was conducted at several levels of complexity in a hierarchical manner to establish its accuracy and reliability (1) supersonic inlet dynamics (2) detonation in single-tube, multicycle environments and (3) system performance and thermodynamic cycle analysis. The progress made in each of the above three areas was reported at the 14th U.S. Office of Naval Research (ONR) Propulsion Meeting [1]. The work performed focused on the following three areas (1) effect of nozzle configuration on PDE performance, (2) single-tube thrust chamber dynamics, and (3) multitube thrust chamber dynamics. 

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