Validation and Verification of reactingPimpleCentralFOAM for Ejector Ramjet Applications
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Bibliographic record
Abstract
View Video Presentation: https://doi.org/10.2514/6.2023-1228.vid A computational fluid dynamics (CFD) validation study for the analysis of compressible flows with combustion using a third-party OpenFOAM solver, reactingPimpleCentralFOAM, is performed for three cases: a one-dimensional (1D) laminar flame, a three-dimensional bluff-body stabilized flame, and a ramjet with a novel intake system operating at static conditions. The 1D laminar flame case was simulated for methane and propane flames for various reaction mechanisms. Results were found to reasonably agree with Cantera for global reaction mechanisms, but significant differences were observed when detailed chemical mechanisms were used. The second validation case compares reactingPimpleCentralFOAM results to experimental data available for a bluff-body stabilized premixed propane–air flame. A reasonable match between experimental and CFD results was obtained for the axial velocity when a modified mixing time scale was used with the default Partially-Stirred Reactor (PaSR) combustion model available in OpenFOAM. However the transverse velocity profiles were found to differ and the velocity fluctuations were generally over-predicted. For the final validation case, the thrust was found to be significantly under-predicted when the default PaSR combustion model was used. A modified PaSR model was implemented into OpenFOAM which scaled the reaction rate by the ratio of turbulent and laminar flame speed. This model was found to improve the prediction of thrust but it was still under-predicted compared to experiment. Both models were found to over-predict the entrainment of air into the engine by the fuel jet.
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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