Hypergolic ignition of hybrid rocket fuels in a slab burner experiment
Bibliographic record
Abstract
Hypergolic ignition systems, where combustion is initiated nearly instantaneously upon contact between the oxidizer and the fuel, can improve the reliability, safety, and simplicity of hybrid rocket engines. Hypergolic performance, first and foremost the ignition delay, is of critical importance as it determines the response time of the propulsion system. To evaluate this performance metric, a novel slab burner experiment is developed to study the hypergolic behavior of hybrid rocket propellants in an engine-like configuration. The liquid oxidizer injection system and the flow conditions implemented in this slab burner are characterized in detail. Two types of experiments are presented. In the first, nitric acid is used essentially for ignition and is injected as a spray into a combustion chamber containing a paraffin-based fuel slab doped with ammonia borane and filled with gaseous oxygen. Rapid hypergolic ignition, in the order of 250 to 3000 ms, with nitric acid and sustained combustion with gaseous oxygen are observed. In the second experiment, concentrated nitric acid is injected into a combustion chamber under an inert atmosphere resulting in significantly slower ignition. The experiments are filmed with a high-speed camera to measure the hypergolic ignition delays and the location of flames. Additionally, the reignition capability of these two systems is evaluated. Successful reignitions are observed with delays greater than the initial hypergolic event. Novelty and significance This study presents an in-depth investigation of hypergolic ignition in hybrid rocket engines. A novel hypergolic slab burner experiment is designed and presented. This experimental setup allows for a detailed analysis of hypergolic ignition delays and combustion dynamics in hybrid rocket propellants, providing valuable insights for improving hypergolic engine reliability and performance. This test configuration allows for providing insights more relevant to oxidizer injection conditions encountered in full-scale hybrid engines. In addition, hypergolic reignition performance are evaluated.
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How this classification was reachedexpand
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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".