High Pressure Subsonic Nucleation in 1D Nozzles — An Experimental Study
Bibliographic record
Abstract
The presence of moisture in steam turbines is known to cause blade erosion and reduce turbine performance. As a result, nucleating wet steam flow has been the topic of both academic and engineering research for many decades. However, almost all of the previous experimental studies on steam nucleation have been carried out under low pressure supersonic flow conditions, either in converging-diverging (Laval) nozzles or in supersonic airfoil cascades. Some recent experimental studies conducted droplet size/wetness measurements within actual turbines, but these tests in general only give qualitative assessment on the nucleation phenomena. They are not intended to study the mechanisms of the nucleating steam flow. In this paper, an experimental study of nucleating wet steam flow under high-pressure subsonic flow conditions is presented. In particular, the world’s first high-pressure subsonic nucleation test rig was designed and built at the GE Global Research Center. This advanced test rig takes high pressure (up to 1000 psia) clean steam with controlled inlet superheat and expands it through 1D subsonic nozzles. The Wilson line location and the length of the nucleation zone are controlled through different combinations of inlet steam pressure and superheat, and overall pressure ratios. An advanced optical measurement system was developed and used to measure the Wilson line, the ensuing condensation zone, and the droplet size and number density generated from nucleation. The flow path in the nozzle is visible through specially designed sapphire windows. The optical system is essentially comprised of two laser-photodiode pairs (405 nm and 689 nm wavelength), which can be traversed along the length of the nozzle. The experiment data have indicated that significant differences exist between high pressure subsonic nucleation and low pressure supersonic nucleation. Further, an in-house 1D analytical tool as well as a 3D multiphase CFD have been used to model the test runs, and reasonable agreements have been obtained. This study has direct application in the design of Nuclear and Concentrated Solar high pressure steam turbines.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".