Laser Doppler Velocimeter Measurements in the Ground Interaction Region of an Impinging Scale Model Jet
Bibliographic record
Abstract
Two-component Laser Doppler Velocimetry measurements were made in the jet plume, impingement region, and outwash region of a scale model jet impinging on a ground plane. The model used for this study is representative of a generic military-style STOVL aircraft in hover. A 13.5mm contoured de Laval nozzle was operated at its design nozzle pressure ratio of 2.93. Velocity measurements were made for ground plate to model separations of 22.9, 12, and 6Dr. Mean velocity measurements in the jet plume and wall jet were compared to previous pitot rake measurements. In general there was good agreement with past data although there was a slight mismatch in measured peak velocities between the two measurement techniques. For plate separations of 12 and 6Dr, axially-directed velocities as high as 250m/s were measured within 0.5Dr of the ground plane. Turbulence intensities as high as 15% of the jet exit velocity were found to be in the shear layer of all jet plumes as well as out to 4Dr in the wall jet for a plate separation of 12Dr. Outwash velocities as high as 25% of the jet exit velocity were found to extend radially out to 7Dr. The decay of peak velocity in the wall jet was found to be approximately inversely proportional to radial position. Spectra obtained for a plate separation of 6Dr showed a distinct tone at several locations in the flow field that agreed well the impingement tone measured previously in the acoustic field. These are large scale motions that have been observed with flow visualizations but have been previously difficult to quantify for supersonic impinging jets.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".