Steepness of Grain Geometry Transitions on Instability Symptom Suppression in Solid Rocket Motor
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Bibliographic record
Abstract
Research towards predicting and quantifying undesirable transient nonlinear axial combustion instability symptoms in solid rocket motors, and the various means for suppressing these symptoms, is being undertaken through the use of a comprehensive numerical model for internal ballistic simulation under dynamic flow, combustion and structural vibration conditions. In the present paper, as a follow-on study of area transition effects, the effect of the steepness of left-to-right internal propellant grain port geometry transitions in suppressing instability symptoms is comprehensively examined. Individual transient simulation runs for unstable cases show the evolution of the axial pressure wave and associated dc shift for the given grain geometry of a reference motor, as initiated by a given pressure disturbance. Limit pressure wave magnitudes are collected for a number of simulation runs for different grain area transition gradients, and mapped on an attenuation trend chart. Within the context of the present study, for one reference motor design and size, it is clear that steeper area transitions are more effective in suppressing wave development. When the effect of acceleration (through structural vibration of the propellant surface) on the combustion process is included in the numerical calculations, one observes substantial differences in burning and internal flow behavior in the presence of axial pressure wave activity, as reflected in individual firing simulations and the corresponding attenuation map.
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Full frame distilled prediction
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)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it