Effect of Transient Gasdynamic Processes on the Impulse of Pulse Detonation Engines
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Bibliographic record
Abstract
Introduction I N a pulse detonation engine (PDE), thrust results from the expansion of the high-pressureand temperature products of a detonation. Much of the effort in PDE development has been focused on the rapid initiation of detonation to achieve detonation in a distance compatible with the dimensions of an engine. The question of whether the impulse generated depends on different gasdynamic processes, such as direct initiation, de agration to detonation transition (DDT), or constant volume explosion, becomes a valid one. In the present study, the impulse produced by a single-cycle hydrogen–oxygen PDE is experimentally investigated.The goal is to determine the effect of transient gasdynamic processes on impulse. The impulse producedby direct initiation is compared to that producedby DDT for two different initiation locations,at the thrust wall and at the open end. The equivalence ratio is varied to control the run-up distance (RUD). The impulse is measured in two ways: the ballistic pendulum method and the integration of the end wall (thrust wall) pressure. The former, the ballistic pendulum method, was rst applied to measuring the impulse generated by a detonation by Nicholls et al. and has recently been used by Cooper et al. and Daniau et al. to measure the effect of obstacles and nozzles on the impulse generated by a single detonation pulse. Harris et al. also used a ballistic pendulum to study the effect of nitrogen dilution and compared the impulse for the cases of direct initiation and DDT initiated from the closed end of the tube. In the ballistic pendulum technique, the amplitude of swing of a pendulum-mounted PDE provides a direct measurement of the total integrated thrust. The latter technique, integrating the end wall pressure, is more typically used in PDE experiments, but will only produce an accurate measurement of impulse if friction and other momentum losses are negligible.
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Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
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Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
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