Entropy generation and second law analysis of pulsed impinging jet
Bibliographic record
Abstract
Purpose – The purpose of this paper is to examine entropy generation rate in the flow and temperature field due pulsed impinging jet on to a flat plate. Heat transfer of pulsed impinging jets has been investigated by many researchers. Entropy generation is one of the parameters related to the second law of thermodynamics which must be analyzed in processes with heat transfer and fluid flow in order to design efficient systems. Effect of velocity profile parameters and various nozzle to plate distances on viscous and thermal entropy generation are investigated. Design/methodology/approach – In this study, the flow and temperature field of a pulsed turbulent impinging jet are simulated numerically by the finite volume method with appropriate boundary conditions. Then, flow and temperature results are used to calculate the rate of entropy generation due to heat transfer and viscous dissipation. Findings – Results show that maximum viscous and thermal entropy generation occurs in the lowest nozzle to plate distance and entropy generation decreases as the nozzle to plate distance increases. Entropy generation in the two early phase of a period in the most frequencies is more than steady state whereas a completely opposite behavior happens in the two latter phase. Increase in the pulsation frequency and amplitude leads to enhancement in entropy generation because of larger temperature and velocity gradients. This phenomenon appears second and even third peaks in entropy generation plots in higher pulsation frequency and amplitude. Research limitations/implications – The predictions may be extended to include various pulsation signal shape, multiple jet configuration, the radiation effect and phase difference between jets. Practical implications – The results of this paper are a valuable source of information for active control of transport phenomena in impinging jet configurations which is used in different industrial applications such as cooling, heating and drying processes. Originality/value – In this paper the entropy generation of pulsed impinging jet was studied for the first time and a comprehensive discussion on numerical results is provided.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".