An extended model for orifice starting jets
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Bibliographic record
Abstract
Starting jets emanating from a straight nozzle and orifices of different orifice-to-tube diameter ratios are investigated using time-resolved particle image velocimetry. The invariants of the motion, namely, the circulation, the hydrodynamic impulse, and the kinetic energy, are measured and compared to the classic slug-flow model, and this for both fixed exhaust speed and fixed diameter-based Reynolds numbers. An extension to the slug-flow model is proposed to account for the contraction the fluid is experiencing when being pushed out through orifice geometries. The contraction coefficients obtained for two-dimensional jets formed through a slit in a channel are applied to the axisymmetric problem. This modified slug-flow model is shown to better predict the invariants of the motion with discrepancies of the order of 10% compared to underpredictions of 130%, 50%, and 120% for the circulation, the hydrodynamic impulse, and the kinetic energy, respectively, using the classic slug-flow model. Moreover, for a fixed target exhaust speed, the model suggests the existence of a maximum in the production of impulse and energy at an orifice-to-tube diameter ratio of about 0.9, which was also observed experimentally for the kinetic energy. Practically speaking, this suggests that the most efficient way of producing a starting jet is using an orifice plate of ratio close to 1, but different from a straight nozzle. Finally, the overpressure correction of Krueger [“The significance of vortex ring formation and nozzle exit overpressure to pulsatile jet propulsion,” Ph.D. thesis (California Institute of Technology, 2001)] is applied and revisited to account for the orifice-to-tube diameter ratio. Overall, good agreement with the present experimental data is found.
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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