Aerodynamics of a Family of Three Highly Loaded Low-Pressure Turbine Airfoils: Measured Effects of Reynolds Number and Turbulence Intensity in Steady Flow
Bibliographic record
Abstract
The steady, midspan aerodynamic performance of a family of three low pressure (LP) turbine airfoils has been investigated in a low-speed cascade wind tunnel. The baseline profile has a Zweifel coefficient of 1.08. To examine the influence of increased loading as well as the loading distribution, two additional airfoils were designed, each with 25% higher loading than the baseline version. All three airfoils have the same design inlet and outlet flow angles. The aerodynamic performance was investigated for Reynolds numbers ranging from 25,000 to 150,000 (based on the axial chord and inlet velocity) and for values of freestream turbulence intensity of 1.5% and 4%. The flow field was measured with a three-hole pressure probe. Also, detailed loading distributions were obtained for all three airfoils using surface static pressure taps. The baseline airfoil and the new aft-loaded airfoil showed a separation bubble on the suction side of the airfoil under most of the conditions examined. In addition, a sudden and intermittent stall was observed at low Reynolds numbers for the new aft-loaded airfoil. The relatively short separation bubble would abruptly “burst” and fail to reattach. As the Reynolds number was decreased over a narrow range, the percentage of time that the flow was fully-separated increased to 100%. By comparison, the separation bubble on the baseline airfoil gradually increased in size in an orderly way as the Reynolds number was decreased. The new front-loaded airfoil provided the most encouraging performance: no separation bubble was present except at the very lowest Reynolds numbers. The absence of a separation bubble also had a favourable effect on the loss behaviour of this airfoil: despite its much higher aerodynamic loading, it exhibited very similar midspan losses to those observed for the baseline airfoil.
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How this classification was reachedexpand
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) | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".