Numerical Analysis of Hovering Tilt-Rotor UAV for Minimum Download and Ground Effect Analysis

Aerodynamic interference test of quad tilt rotor aircraft in wind tunnel

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019852827 ◽

2019 ◽

Vol 233 (15) ◽

pp. 5553-5566 ◽

Cited By ~ 2

Author(s):

Kun Chen ◽

Zhiwei Shi ◽

Shengxiang Tong ◽

Yizhang Dong ◽

Jie Chen

Keyword(s):

Wind Tunnel ◽

Reference Value ◽

Ground Effect ◽

Open Loop ◽

Force Balance ◽

Scale Model ◽

Operating Condition ◽

Tilt Rotor ◽

Interference Test ◽

Aerodynamic Interference

There is an obvious aerodynamic interference problem that occurs for a quad tilt rotor in near-ground hovering or in the conversion operating condition. This paper presents an aerodynamic interference test of the quad tilt rotor in a wind tunnel. A 1:35 scale model of the quad tilt rotor is used in this test. To substitute for the ground, a moveable platform is designed in a low-speed open-loop wind tunnel to simulate different flight altitudes of the quad tilt rotor in hovering or forward flight. A rod six-component force balance is used to measure the loads on the aircraft, and the flow field below the airframe is captured using particle image velocimetry. The experimental results show that the ground effect is significant when the hover height above the ground is less than the rotor diameter of the quad tilt rotor aircraft, and the maximum upload of the airframe is approximately 12% of the total vertical thrust with the appearance of obvious fountain flow. During the conversion operating condition, the upload of the airframe is reduced compared with that in the hovering state, which is affected by rotor wake and incoming flow. The aerodynamic interference test results of the quad tilt rotor aircraft have important reference value in power system selection, control system design, and carrying capacity improvement with the advantage of ground effect.

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An Experimental Investigation of a Quad Tilt Rotor in Ground Effect

21st AIAA Applied Aerodynamics Conference ◽

10.2514/6.2003-3517 ◽

2003 ◽

Cited By ~ 3

Author(s):

Anand Radhakrishnan ◽

Fredric Schmitz

Keyword(s):

Experimental Investigation ◽

Ground Effect ◽

Tilt Rotor

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Numerical Analysis of the Ground Effect on Insect Hovering

Journal of Hydrodynamics ◽

10.1016/s1001-6058(08)60022-0 ◽

2008 ◽

Vol 20 (1) ◽

pp. 17-22 ◽

Cited By ~ 11

Author(s):

Tong Gao ◽

Nan-sheng Liu ◽

Xi-yun Lu

Keyword(s):

Numerical Analysis ◽

Ground Effect

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An Experimental Investigation of Ground Effect on a Quad Tilt Rotor in Hover

Journal of the American Helicopter Society ◽

10.4050/jahs.60.012002 ◽

2015 ◽

Vol 60 (1) ◽

pp. 1-14 ◽

Cited By ~ 3

Author(s):

Anand Radhakrishnan Mylapore ◽

Fredric H. Schmitz

Keyword(s):

Flow Visualization ◽

Large Scale ◽

Static Pressure ◽

Ground Effect ◽

Pressure Measurements ◽

Physical Processes ◽

Tilt Rotor ◽

Confidence Levels ◽

Wing Model ◽

Power Measurements

The performance of a 0.031 geometrically scaled fuselage/wing model of a Quad Tilt Rotor (QTR) operating in helicopter mode while hovering in-ground effect (IGE) and out-of-ground effect (OGE) was experimentally studied. The effect of ground proximity was tested by varying the height of the model above the ground. Measurements included download on the airframe; thrust, torque, and rpm of the rotors; and static pressures along the centerline of the bottom of the fuselage. Fixedpitch propellers were used to model the rotors. The downwash distributions of the rotors were measured and compared well with large-scale V-22 rotor measurements. Tuft flow visualization was used to identify the physical processes causing changes in the download and static pressure measurements. The uncertainty of the measured quantities was determined to 95% confidence levels. A significant download (9 ± 0.5% of the rotor thrust) was observed in hover, OGE. The download reduced substantially IGE and become an upload (8.5 ± 0.5% of the rotor thrust) when the wheels of the QTR were on the ground. Flow visualization and pressure measurements suggest that the upload IGE is caused by the interaction of the wakes from the four rotors that are turned parallel to the ground and meet under the fuselage. The measured download, coupled with power measurements, indicate that for a given power the available vehicle thrust significantly increases IGE.

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