The prediction and validation of hover performance and detailed blade loads

Sven Schmitz, Jean Jacques Chattot, Mahendra Bhagwat, Marvin A. Moulton, Francis X. Caradonna

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


This paper describes a hybrid Computational Fluid Dynamics (CFD) method for the prediction of isolated rotor hover performance. The hybrid analysis is one that combines a local Reynolds Averaged Navier-Stokes (RANS) solver to resolve the near-blade flow with a Vorticity-Embedding (VE) potential-flow CFD analysis for the wake. The paper describes the VE method as well as recent modeling improvements. However, this paper mainly concerns validation of the computational results. The primary sources of validation data used herein are those for a model scale rotor tested in two different facilities and with different drive/balance/shroud systems. The comparisons entail two parts: (1) comparisons of wake trajectories and ensuing blade loads (surface pressures and integrated sectional thrust and torque), and (2) comparison with performance data (total thrust and torque from balance measurements). The wake/load comparisons with the test data demonstrate that the current method has the ability to compute hover wakes (and ensuing pressure-related loads) with an accuracy and speed that is unusual. The performance comparisons, however, are complicated by the fact that the two data sets do not agree to the level of accuracy required for validation. Present computations are in reasonable agreement with one set of data, though with sufficient difference to suggest that drag modeling requires further improvement. The paper also demonstrates computation of a highly tapered-tip rotor that encounters stall - again with a discussion of wakes, loads and performance. This latter case shows a definite need to improve separated flow modeling. The present hybrid method is concluded to be a practical means of computing detailed blade loads and performance without incurring the high cost and usual numerical errors of the wake computation. It is suggested that further development of hover CFD methods requires validation and test data in greater detail and variety than currently exists.

Original languageEnglish (US)
Title of host publicationAHS Specialists' Conference on Aeromechanics 2008
Number of pages19
StatePublished - 2008
EventAHS Specialists' Conference on Aeromechanics 2008 - San Francisco, CA, United States
Duration: Jan 23 2008Jan 25 2008

Publication series

NameAmerican Helicopter Society International - AHS Specialists' Conference on Aeromechanics 2008


OtherAHS Specialists' Conference on Aeromechanics 2008
Country/TerritoryUnited States
CitySan Francisco, CA

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Control and Systems Engineering


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