Experimental investigation of the helicopter blade tip shape effects on aerodynamic performance and tip vortex characteristics

Uluocak, Sinem
This study experimentally investigates the effects of different rotor blade tip shapes on the rotor aerodynamic performance and the tip vortex characteristics in hovering flight. Force, torque and flow field measurements were performed on a 1.3 m diameter 5-bladed model rotor for four different blades: rectangular (RECT), anhedral (ANHD), tapered-swept (TAPER) and tapered-swept-anhedral (TSA). Thrust and torque measurements show that all tip modifications have a positive effect on the aerodynamic performance when compared to the RECT tip configuration especially at low blade loadings. Overall, the ANHD tip configuration gives the best aerodynamic performance at high blade loadings. It reaches a maximum figure of merit (FOM) value of 0.67 and provides a FOM improvement of approximately 0.03 compared to the RECT blade at the tip Mach number (Mtip) of 0.3. Phase-locked particle image velocimetry measurements were conducted at 6◦ intervals between 0◦ -72◦ phase/wake ages at the selected pitch angle of 16◦ and Mtip = 0.4. It is observed that tip modifications change the tip vortex trajectory by increasing radial convection speed and decreasing axial convection speed. ANHD reduces the maximum vortex tangential velocity up to 20%; the TAPER and the TSA reduces it up to 30%. The minimum tip-vortex circulation level is achieved in the case of the ANHD blade, which is in agreement with the highest FOM obtained with this blade.


Experimental investigation of tip anhedral effects on the aerodynamics of a model helicopter rotor in hover
Uluocak, Sinem; Perçin, Mustafa; Uzol, Oğuz (2021-06-01)
This study experimentally investigates the effects of tip anhedral on the rotor aerodynamic performance and the tip vortex characteristics in hovering flight. A five-bladed scaled helicopter rotor with blades that have either rectangular (baseline) or anhedral tip geometries was used as the experimental model. Thrust and torque measurements were performed at the tip Mach numbers (Mtip) of 0.3 and 0.4 at five different pitch angles. In addition, flow field measurements via phase-locked particle image velocim...
Experimental investigation of the effects of different helicopter rotor tip geometries on aerodynamic performance and tip vortex characteristics
Uluocak, Sinem; Hazaveh, Hooman Amiri; Perçin, Mustafa; Akpolat, M Tuğrul; Uzol, Oğuz (Netherlands Association of Aeronautical Engineers; 2018-09-05)
In this study, the effects of different tip geometries (rectangular, anhedral, swept-tapered and swept-tapered-anhedral) on the rotor hover performance and tip vortex characteristics are investigated experimentally. A scaled rotor model set-up, instrumented with thrust and torque sensors, is used for aerodynamic performance measurements in hover and a two-dimensional (2D) particle image velocimetry (PIV) is used to obtain the tip vortex characteristics such as vortex trajectory, maximum tangential velocity,...
Experimental analysis of flow structure on moderate sweep delta wing
Öztürk, İlhan; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2014)
Experimental investigation of flow over a 45° moderate swept delta wing is performed using laser illuminated smoke visualization, surface pressure measurements, and Laser Doppler Anemometry (LDA) techniques in low-speed wind tunnel. The formation of leading-edge vortices and their breakdown, and three-dimensional separation from the surface of the wing are studied at broad range of attack angles and Reynolds numbers. Smoke visualizations are performed at three different cross flow planes along with vortex a...
A Computational analysis on rotor-propeller arm interaction in hovering flight
Yener, Serkan.; Perçin, Mustafa; Department of Aerospace Engineering (2019)
This study presents a computational analysis on the interaction between rotor and different rotor frame-arm geometries in hovering flight. The influence of the frame arm on the aerodynamic performance of the rotor is assessed by using commercially available computational fluid dynamics (CFD) solver software ANSYS Inc. Fluent 17. Numerical results are validated for hovering and forward vertical climb flight conditions with thrust and torque measurements conducted on a 16x4 carbon fiber propeller. The thrust ...
Experimental Investigation of the Effects of Winglets on the Tip Vortex Behavior of a Model Horizontal Axis Wind Turbine Using Particle Image Velocimetry
Ostovan, Yasar; Akpolat, M. Tugrul; Uzol, Oğuz (2019-02-01)
This study presents an experimental investigation on the effects of winglets on the near wake flow around the tip region and on the tip vortex characteristics downstream of a 0.94 m diameter three-bladed horizontal axis wind turbine (HAWT) rotor. Phase-locked 2D particle image velocimetry (PIV) measurements are performed with and without winglets covering 120 deg of azimuthal progression of the rotor. The impact of using winglets on the flow field near the wake boundary as well as on the tip vortex characte...
Citation Formats
S. Uluocak, “Experimental investigation of the helicopter blade tip shape effects on aerodynamic performance and tip vortex characteristics,” M.S. - Master of Science, Middle East Technical University, 2019.