Effects of Duct Shape on a Ducted Propeller Performance

Abstract

Performance characteristics and velocity field of a ducted propeller in hover and axial flight conditions are investigated experimentally. Five different circular duct shapes has been tested. Effect of duct geometry is studied by means of measurements at various flow conditions. Velocity field upstream and downstream of the propeller, axial force acting on each component of the propulsive system, rotor speed and torque are measured. Pressure distribution on duct inner and outer surfaces is also investigated. Experimental results obtained for open and ducted propellers are compared. Nomenclature= duct inner diameter at propeller plane J = advance ratio (U ∞C /nD) K P = pressure coefficient L = duct length n = revolutions per second N = revolutions per minute P = power (2nQ) Q = torque T = thrust U = mean velocity U ∞ = free stream velocity U ∞C = corrected free stream velocity x = axial direction r = radial direction η = efficiency

Review on ducted fans for compound rotorcraft

“…Yilmaz et al (36) 8.33 8.33 0.23 A NA NA -Y Pressure and velocity field measured Bahram (26) 8 . Early experiments on ducted fans.…”

“…7(h)) (34,41) . More recently, Yilmaz et al (36) examined five different circular duct shapes using the same two-bladed propeller and a constant RPM (Fig. 7(j)).…”

“…(30) (d) Graf et al (31) (e) Pereira. (3) (f) Akturk et al (32) (g) Ohanian et al (33) (h) Akturk and Camci (34) (i) Rhee et al (35) (j) Yilmaz et al (36) (k) Bahram. (26) …”

Parametric study of aerodynamic performance of equivalent ducted/un-ducted rotors

“…Many of these tests used large, real-scale ducted rotor models, and were well documented, but focused on the performance of specific designs. Recent experimental studies [6][7][8] mostly aimed at Unmanned/Micro Aerial Vehicle (UAV/MAV) applications, hence the Reynolds numbers were small and the compressibility effects were only minor. Moreover, few tests disclosed their detailed geometric definitions and test data due to commercial restrictions.…”

Experimental characterization of noise radiation from a ducted propeller of an unmanned aerial vehicle

“…This suppression leads to a reduction in tip induced drag. 6,7 Additionally, ducts provide protection by containing the blades in the event of blade failure.…”