Thermometry and Velocimetry in Supersonic Flows via Scanned Wavelength-Modulation Absorption Spectroscopy
Bibliographic record
Abstract
A tunable diode laser-based H2O absorption diagnostic has been developed to characterize transient phenomena within the Stanford Expansion Tube Flow Facility. Key parameters provided by the diagnostic include the temperature, H2O mole-fraction and velocity time-histories of the supersonic test gas, as well as the arrival time of the test gas contact surfaces. The presence of water within the test gas affords well-established rovibrational transitions near 1.4 µm that are probed using scanned wavelength-modulation absorption spectroscopy with second harmonic detection (scanned-WMS-2f). The scannedWMS-2f technique offers the sensitivity and noise resistance necessary for temperature and mole-fraction measurements within the harsh conditions of the expansion tube test section. A rigorous scanned-WMS-2f theory has been developed to account for non-ideal laser characteristics prompted by short test times and high flow velocities and is employed for the first time in an absorption diagnostic. Furthermore, by implementing a crossed beam laser configuration, second harmonic Doppler shift velocimetry is performed in concert with the temperature and mole-fraction measurements to provide flow velocity data. The measurements carried out with this sensor provide a quantitative characterization of the test gas conditions produced in the expansion tube and thus provide an essential foundation for supersonic combustion experimentation within the facility.
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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) | 0.005 | 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".