Numerical investigation of aerodynamics and aeroacoustics of helical Darrieus wind turbines
Bibliographic record
Abstract
View Video Presentation: https://doi.org/10.2514/6.2023-3641.vid The aerodynamic and aeroacoustic characteristics of three scaled model Helical-Darrieus vertical axis wind turbines (VAWT) with helix angles of 45°, 60°, and 120° are examined at a fixed rotational speed of 3500 rpm. A 3D Lattice Boltzmann/Very Large Eddy Simulation is performed using the commercial flow solver PowerFLOW. The predicted power coefficient for the helix 60° turbine demonstrates good agreement with available experimental data. A decrease in blade loading is observed with increasing helix angles. The helical twist generates a mean flow in the spanwise direction, leading to asymmetry in blade loading and wall pressure spectra along the span. The primary flow structures involve tip vortices and their interaction with end plates. Additionally, the helix twist aids in reducing blade wake interaction, as shed structures do not directly impinge on the incoming blade. The flow solution is then also coupled with an in-house aeroacoustic propagation code, SherFWH, based on the Ffowcs Williams and Hawkings analogy for far-field noise propagation. The present numerical predictions for noise at an observer location show excellent agreement with available experimental data for the helix 45° turbine. The leading section of the blade exhibits high wall pressure fluctuations over the azimuthal revolution of the turbine, forming the dominant noise contribution at the blade passing frequencies (BPF), while smaller structures at the blade-end plate junction also contribute to high-frequency broadband noise. As the helix angle increases, both the tonal peaks at the BPFs and the broadband noise decrease due to enhanced flow mixing and three dimensional flow. A 20 dB decrease is seen at the first BPF tonal peak for the helix 120° turbine. Moreover, the helix angle also alters the orientation of the noise directivity, aligning it along the helix angle.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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 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".