Quantification of the Ground Effect on the Aerodynamic Interferences of a Coaxial Rotor System.

Saved in:

Bibliographic Details
Title:	Quantification of the Ground Effect on the Aerodynamic Interferences of a Coaxial Rotor System.
Authors:	Moore, Zachary¹, Silwal, Lokesh², Vijayaraj, Aditya¹, Raghav, Vrishank³
Source:	Journal of the American Helicopter Society. Jan2026, Vol. 71 Issue 1, p1-13. 13p.
Subjects:	Rotor dynamics, Rotors, Applied sciences, Rotorcraft, Momentum (Mechanics), Aerodynamics
Abstract:	The aerodynamic interactions of a counterrotating coaxial rotor (CCR) hovering in-ground effect (IGE) were investigated using a mechanically decoupled two-bladed rotor facility. A momentum theory-based theoretical framework was developed to quantify the aerodynamic interactions. Baseline measurements were performed on a single rotor out-of-ground effect (OGE) and IGE, and a coaxial rotor OGE. Then, coaxial rotor IGE measurements were conducted to evaluate the competing rotor-rotor and rotor-ground interactions. The coaxial rotor experienced rotor-ground interactions similar to a single rotor at multiple IGE conditions. At the most extreme IGE condition studied, the rotor-ground interaction reduced the required power of the CCR by roughly 30%. However, changes in the rotor-rotor interactions at this condition significantly altered the performance of the upper and lower rotors, with the lower rotor necessitating 8% more induced power while the upper rotor required 8% less power when compared to the respective performance characteristics of OGE. Flow field measurements indicated that the wake of the upper rotor contracts less in the presence of the ground, which exacerbates the negative performance effect on the lower rotor. [ABSTRACT FROM AUTHOR]
	Copyright of Journal of the American Helicopter Society is the property of American Helicopter Society dba Vertical Flight Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	The aerodynamic interactions of a counterrotating coaxial rotor (CCR) hovering in-ground effect (IGE) were investigated using a mechanically decoupled two-bladed rotor facility. A momentum theory-based theoretical framework was developed to quantify the aerodynamic interactions. Baseline measurements were performed on a single rotor out-of-ground effect (OGE) and IGE, and a coaxial rotor OGE. Then, coaxial rotor IGE measurements were conducted to evaluate the competing rotor-rotor and rotor-ground interactions. The coaxial rotor experienced rotor-ground interactions similar to a single rotor at multiple IGE conditions. At the most extreme IGE condition studied, the rotor-ground interaction reduced the required power of the CCR by roughly 30%. However, changes in the rotor-rotor interactions at this condition significantly altered the performance of the upper and lower rotors, with the lower rotor necessitating 8% more induced power while the upper rotor required 8% less power when compared to the respective performance characteristics of OGE. Flow field measurements indicated that the wake of the upper rotor contracts less in the presence of the ground, which exacerbates the negative performance effect on the lower rotor. [ABSTRACT FROM AUTHOR]
ISSN:	00028711
DOI:	10.4050/JAHS.71.012005