Bibliographic Details
| Title: |
Using Model-Scale Tandem-Rotor Measurements in Ground Effect to Understand Full-Scale CH-47D Outwash. |
| Authors: |
Ramasamy, Manikandan1 manikandan.ramasamy.civ@mail.mil, Yamauchi, Gloria K.2 |
| Superior Title: |
Journal of the American Helicopter Society. Jan2017, Vol. 62 Issue 1, p1-14. 14p. |
| Subject Terms: |
*ROTORS (Helicopters), *AZIMUTH, *FUSELAGE (Airplanes), *VELOCIMETRY, *FLUID flow |
| Abstract: |
Downwash and outwash characteristics of a model-scale tandem-rotor system in the presence of the ground were analyzed by identifying and understanding the physicalmechanisms contributing to the observed flow field behavior. A building block approach was followed in simplifying the problem, separating the effects of the fuselage, effects of one rotor on the other, etc. Flow field velocities were acquired in a vertical plane at four aircraft azimuths of a small-scale tandem rotor system using the particle image velocimetry technique for radial distances up to four times the rotor diameter. Results were compared against full-scale CH-47D measurements. Excellent correlation was found between the small- and full-scale mean flow fields (after appropriate normalization using rotor and wall jet parameters). Following the scalability analysis, the effect of rotor height on the outwash was also studied. Close to the aircraft, an increase in rotor height above ground decreased the outwash velocity at all aircraft azimuths. However, farther away, the longitudinal and lateral axes of the aircraft showed increasing and decreasing outwash velocities, respectively, with increasing rotor height. Baseline rotor measurements were made out-of-ground effect to understand the nature of inflow distribution for realistic rotor configurations and their modified characteristics in the presence of the ground. [ABSTRACT FROM AUTHOR] |
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| Database: |
Academic Search Premier |