Quad Tilt Rotor Aerodynamics in Ground Effect

2005 ◽  
Author(s):  
Anand Radhakrishnan ◽  
Fredric Schmitz
Keyword(s):  
Ground Effect ◽  
Rotor Aerodynamics ◽  
Tilt Rotor

Aerodynamic interference test of quad tilt rotor aircraft in wind tunnel

2019 ◽  
Vol 233 (15) ◽  
pp. 5553-5566 ◽  
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.

Preliminary Design of Hybrid-Electric Propulsion Systems for Emerging UAM Rotorcraft Architectures

2021 ◽  
Author(s):  
Chana Anna Saias ◽  
Ioannis Goulos ◽  
Ioannis Roumeliotis ◽  
Vassilios Pachidis ◽  
Marko Bacic
Keyword(s):  
Electric Propulsion ◽  
Flight Test ◽  
Preliminary Design ◽  
Propulsion Systems ◽  
Rotor Aerodynamics ◽  
Tilt Rotor ◽  
Integrated Methodology ◽  
Hybrid Electric ◽  
Battery Energy ◽  
Optimal Implementation

Abstract The increasing demands for air-taxi operations together with the ambitious targets for reduced environmental impact have driven significant interest in alternative rotorcraft architectures and propulsion systems. The design of Hybrid-Electric Propulsion Systems (HEPSs) for rotorcraft is seen as being able to contribute to those goals. This work aims to conduct a comprehensive design and trade-off analysis of hybrid powerplants for rotorcraft, targeting enhanced payload-range capability and fuel economy. An integrated methodology for the design, performance assessment and optimal implementation of HEPSs for conceptual rotorcraft has been developed. A multi-disciplinary approach is devised comprising models for rotor aerodynamics, flight dynamics, HEPS performance and weight estimation. All models are validated using experimental or flight test data. The methodology is deployed for the assessment of a hybrid-electric tilt-rotor, modelled after the NASA XV-15. This work targets to provide new insight in the preliminary design and sizing of optimally designed HEPSs for novel tilt-rotor aircraft. The paper demonstrates that at present, current battery energy densities (250Wh/kg) severely limit the degree of hybridization if a fixed useful payload and range are to be achieved. However, it is also shown that if advancements in battery energy density to 500Wh/kg are realized, a significant increase in the level of hybridization and hence reduction of fuel burned and carbon output relative to the conventional configuration can be attained. The methodology presented is flexible enough to be applied to alternative rotorcraft configurations and propulsion systems.

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

2015 ◽  
Vol 60 (1) ◽  
pp. 1-14 ◽  
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.

Rotor Aerodynamics in Ground Effect at Low Advance Ratios

1984 ◽  
Vol 29 (1) ◽  
pp. 48-55 ◽  
Author(s):  
H. C. Curtiss ◽  
M. Sun ◽  
W. F. Putman ◽  
E. J. Hanker
Keyword(s):  
Ground Effect ◽  
Rotor Aerodynamics

Numerical-experimental correlation of hovering rotor aerodynamics in ground effect

2020 ◽  
Vol 106 ◽  
pp. 106079
Author(s):  
Claudio Pasquali ◽  
Jacopo Serafini ◽  
Giovanni Bernardini ◽  
Joseph Milluzzo ◽  
Massimo Gennaretti
Keyword(s):  
Ground Effect ◽  
Rotor Aerodynamics ◽  
Experimental Correlation

scholarly journals Hurdle-Hop Simulation of Tilt-Rotor Aircraft Based on Optimal Control Theory

2020 ◽  
Vol 38 (6) ◽  
pp. 1266-1274
Author(s):  
Jinhe Chen ◽  
Zhengzhong Wang ◽  
Hongyuan Tian
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Optimal Control Theory ◽  
Ground Effect ◽  
Simulation Method ◽  
Programming Algorithm ◽  
Multiple Shooting ◽  
Inverse Simulation ◽  
Tilt Rotor ◽  
Multiple Shooting Method

Aiming at simulating the hurdle-hop of tilt-rotor aircraft in forward flight near the ground, two models of numerical simulation and analysis based on optimal control theory were proposed. Firstly, Longitudinal flight dynamic model for tilt-rotor was modified considering the influence of ground effect. Secondly, the first model is combined with predicted trajectory from inverse simulation method, the inverse model of hurdle-hop of tilt-rotor is established based on optimal trajectory, and the second model is the optimal control model of unpredicted trajectory, which is formulated from the reasonable function of objective, path and boundary constraints for hurdle-hop with detailed analysis, solved two models by direct multiple shooting method and nonlinear programming algorithm. Finally, XV-15 as the sample vehicle. Two models for hurdle-hop based on optimal control theory was calculated, the history of optimal flight trajectory and control are given.

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