Experimental Investigation into Performance of Laval Nozzles for Reaction Turbines
Bibliographic record
Abstract
Abstract Large resources of thermal and industrial waters at a temperature of 100–150°С can be employed to generate electricity in both a single-circuit thermal cycle with direct usage of natural steam in condensing turbines and a double-circuit cycle with a low-boiling working fluid. Both options require high capital expenditures for their implementation. A new power-generation method on the basis of low-grade heat is to install a full-flow hydro-steam turbine (HST), which utilizes the heat of separated liquid from a geothermal station or the heat of industrial waters, in a single-circuit thermal cycle. Capital expenditures for these units are much lower since special equipment for preparation of the working fluid is not required. The efficiency of a hydro-steam turbine is directly related to the efficiency of its main element, which is the Laval nozzle. Designing this turbine requires reliable data on the performance of a Laval nozzle with a high expansion ratio when it operates on highly subcooled water. Such information can only be obtained experimentally since this region of operation of Laval nozzles has been poorly studied as of yet. To determine the required characteristics of the nozzles, an experimental setup was designed and manufactured with a set of Laval nozzles, including nozzles with different opening angles of the diverging section and nozzles with an oblique cut. The working fluid was water under conditions close to the operating conditions in an HST. The results are presented of the experimental study of Laval nozzles in a wide range of expansion ratios for operation on boiling water. The experiments were performed at different pressures downstream of the nozzle, and their results were compared with previously obtained experimental data. The experimental setup and design features of the nozzle are described. The experimental data on the flow coefficient, velocity coefficient, expansion ratio, initial conditions, nozzle shapes, and size effect, on which the conclusions made are based, have been analyzed. Characteristics have been found that enable us to predict the efficiency of a reaction hydro-steam turbine and properly calculate its output.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".