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Numerical Analysis of a Cycloidal Rotor Under Diverse Operating Conditions and Altitudes

Universidade Da Beira Interior-Mehdi Habibnia Rami, Jose Pascoa
  • Technical Paper
  • 2019-01-1872
To be published on 2019-09-16 by SAE International in United States
The current paper deals with the numerical study of the downwash flowfield characteristics in a cycloidal rotor. In an aircraft equipped with this kind of thruster, the downwash flow plays significant role in different flight modes. The interaction of this downwash jet with ground in effective height levels is studied using CFD simulations. Several operating conditions like pitching oscillation angles, rotation speeds and height levels are all considered in this work. The results declare that close-ground operating states augments the efficiency of cyclorotor. The vertical and horizontal forces of a single blade is also analyzed in a complete cycloid in different operating conditions. A lead and lag in maximum and minimum extremes of force curves of a single blade cycloid is obtained while being subjected to different functional conditions. These results strongly assure that an active control of both pitching oscillation and rotation speed is essential in operating at the optimum desired state.
 
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Experimental Aerodynamic Simulation of Glaze Ice Accretion on a Swept Wing

Federal Aviation Administration Technical Center-Timothy G. Smith
NASA John Glenn Research Center-Andy P. Broeren, Mark G. Potapczuk
Published 2019-06-10 by SAE International in United States
Aerodynamic assessment of icing effects on swept wings is an important component of a larger effort to improve three-dimensional icing simulation capabilities. An understanding of ice-shape geometric fidelity and Reynolds and Mach number effects on iced-wing aerodynamics is needed to guide the development and validation of ice-accretion simulation tools. To this end, wind-tunnel testing was carried out for 8.9% and 13.3% scale semispan wing models based upon the Common Research Model airplane configuration. Various levels of geometric fidelity of an artificial ice shape representing a realistic glaze-ice accretion on a swept wing were investigated. The highest fidelity artificial ice shape reproduced all of the three-dimensional features associated with the glaze ice accretion. The lowest fidelity artificial ice shapes were simple, spanwise-varying horn ice geometries intended to represent the maximum ice thickness on the wing upper surface. The results presented in this paper show that changes in Reynolds and Mach number have only a small effect on the iced-wing aerodynamics relative to the clean-wing configuration. Furthermore, the addition of grit roughness to some lower-fidelity artificial ice…
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Numerical Simulation of Aircraft and Variable-Pitch Propeller Icing with Explicit Coupling

ANSYS Inc.-Isik Ozcer, Guido S. Baruzzi, Miraj Desai, Maged Yassin
Published 2019-06-10 by SAE International in United States
A 3D CFD methodology is presented to simulate ice build-up on propeller blades exposed to known icing conditions in flight, with automatic blade pitch variation at constant RPM to maintain the desired thrust. One blade of a six-blade propeller and a 70-passenger twin-engine turboprop are analyzed as stand-alone components in a multi-shot quasi-steady icing simulation. The thrust that must be generated by the propellers is obtained from the drag computed on the aircraft. The flight conditions are typical for a 70-passenger twin-engine turboprop in a holding pattern in Appendix C icing conditions: 190 kts at an altitude of 6,000 ft. The rotation rate remains constant at 850 rpm, a typical operating condition for this flight envelope. Two icing conditions are simulated: air static temperature -23 °C, LWC 0.2 g/m3 and MVD 20 microns resulting in rime ice, and air static temperature -16 °C, LWC 0.3 g/m3 and MVD 20 microns resulting in mixed ice with rime to glaze transition in the radial direction. The ice shapes in both conditions are assumed to remain intact and…
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Sound Analysis Method for Warble Noise in Electric Actuators

General Motors-Nathan T. Parker
Published 2019-06-05 by SAE International in United States
Multiple automotive applications exist for small electric motors that are activated by vehicle occupants for various functions such as window lifts and seat adjusters. For such a motor to be described as high quality, not only should the sound it produces be low in amplitude, but it also needs to be free from pulsations and variations that might occur during its (otherwise) steady-state operation. If a motor’s sound contains pulsations or variations between 2 and 8 cycles per second, the variation is described as warble. To establish performance targets for warble noise at both the vehicle and component level a way to measure and quantify the warble noise must be established. Building on existing sound quality metrics such as loudness and pitch variation, a method is established by which processed sound data is put through a secondary operation of Fourier analysis. Thus warble can be reduced to a single value, and in this way, noise engineers have a basis to measure and report warble, and to facilitate product development with A/B comparisons. Depending on its…
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Use of Cellphones as Alternative Driver Inputs in Passenger Vehicles

Clemson University-Chengshi Wang, Kim Alexander, Philip Pidgeon, John Wagner
Published 2019-04-02 by SAE International in United States
Automotive drive-by-wire systems have enabled greater mobility options for individuals with physical disabilities. To further expand the driving paradigm, a need exists to consider an alternative vehicle steering mechanism to meet specific needs and constraints. In this study, a cellphone steering controller was investigated using a fixed-base driving simulator. The cellphone incorporated the direction control of the vehicle through roll motion, as well as the brake and throttle functionality through pitch motion, a design that can assist disabled drivers by excluding extensive arm and leg movements. Human test subjects evaluated the cellphone with conventional vehicle control strategy through a series of roadway maneuvers. Specifically, two distinctive driving situations were studied: a) obstacle avoidance test, and b) city road traveling test. A conventional steering wheel with self-centering force feedback tuning was used for all the driving events for comparison. Based on the lane position and vehicle response data collected, the operators’ lane tracking capability during city road traveling was slightly inferior using a cellphone compared to traditional steering wheel. However, in extreme maneuvers like obstacle avoidance…
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Model-Based Pitch Control for Distributed Drive Electric Vehicle

Tongji University-Yize Yu, Lu Xiong, Zhuoping Yu, Xing Yang, Yuye Hou, Bo Leng
Published 2019-04-02 by SAE International in United States
On the dual-motor electric vehicle, which is driven by two electric motors mounted on the front and rear axles respectively, longitudinal dynamic control and electro-dynamic braking can be achieved by controlling the torque of front and rear axle motors respectively. Suspension displacement is related to the wheel torque, thus the pitch of vehicle body can be influenced by changing the torque distribution ratio. The pitch of the body has a great influence on the vehicle comfort, which occurs mainly during acceleration and braking progress. Traditionally active suspension is adopted to control the pitch of body. Instead, in this paper an ideal torque distribution strategy is developed to limit the pitch during acceleration and braking progress. This paper first explores the relationship between the torque distribution and the body pitch through the real vehicle test, which reveals the feasibility of the vehicle comfort promotion by optimizing the torque distribution coefficient. A two-degree-of-freedom semi-vehicle model is established according to the actual vehicle parameters. Based on the vehicle model, the control system is established to minimize the pitch…
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An Analysis of Sport Bike Motorcycle Dynamics during Front Wheel Over-Braking

Momentum Engineering Corp.-Edward Fatzinger, Jon Landerville, Jeffrey Bonsall, Daniel Simacek
Published 2019-04-02 by SAE International in United States
There is extensive literature on motorcycle skid/brake to stop testing on a host of motorcycle types, rider experience, brake system configurations and the associated deceleration rates. Very little information exists on deceleration rates involved with over-braking the front wheel. The subject of this paper addresses the deceleration rates of sport bike type motorcycles during over-braking of the front wheel. Based on the physics of a two-wheeled vehicle like the motorcycle, once the front wheel is over-braked and becomes locked, the rider has very little time to recover from the skid and often times falls. Another over-braking scenario, especially on sport bike type motorcycles, is the possibility of the rear wheel lifting and pitching over the front wheel. During the initial phase of braking, weight transfer to the front wheel occurs creating a greater level of traction. As the motorcycle begins to fall or pitch over, the weight on the front wheel decreases significantly and therefore the frictional force decreases significantly as well. The goal of this publication was to perform maximum front wheel brake testing…
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Vehicle Distance Measurement Algorithm Based on Monocular Vision and License Plate Width

Tongji University-Jian Zhong, Xinbo Chen, Yibing Peng, Yan Li
Published 2019-04-02 by SAE International in United States
In order to avoid the influence of the change of the camera pitch angle and the variation of the height of the ground on the ranging accuracy, improve the real-time performance of the algorithm by substituting the current widely-used monocular vision ranging algorithm which builds the optical model based on the shadow of the vehicle floor and the lane line, as well as avoid the classification of vehicle detection, a vehicle distance measurement algorithm based on monocular vision and license plate width is established. Firstly, the target image acquisition and preprocessing are studied. Then the paper studies the license plate image location segmentation method based on accelerated template matching. On this basis, the algorithm for obtaining the ratio of license plate width to image width is studied, and the function of vehicle distance and license plate ratio width is established. The actual vehicle test shows that the relative average deviation of the algorithm is 0.5% and the standard deviation of 10 repetitive experiments is 0.000216. The accuracy, repeatability and robustness of the algorithm are good.
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Attitude Control of the Vehicle with Six In-Wheel Drive and Adaptive Hydro Pneumatic Suspensions

Tsinghua University-Boxin Li, Gangtie Zheng, Zhaokui Wang
Published 2019-04-02 by SAE International in United States
The ability of actively adjusting attitude provides a great advantage for those vehicles used in special environments such as off-road environment with extreme terrains and obstacles. It can improve vehicles’ stability and performance. This paper proposes an attitude control system for realizing the active attitude adjustment and vehicle motion control in the same time. The study is based on a vehicle with six wheel independent drive and six independent suspensions (6WIDIS), which is a kind of unmanned vehicle with six in-wheel drives and six independent hydro pneumatic suspensions. With the hydro- pneumatic suspensions, the vehicle’s attitude can be actively adjusted. This paper develops a centralized- distributed control strategy with attitude information obtained by multi-sensor fusion, which can coordinate the complex relationship among the six wheels and suspensions. The attitude control system consists of three parts. The first part is the attitude determination that includes attitude sensors and a method to measure any quantity sensitive to attitude and determine the real-time vehicle status. The second part is the attitude adjustment that computes the input torques to…
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INSERT, SCREW THREAD, HELICAL COIL, METRIC SERIES, FREE RUNNING, CRES, UNCOATED

E-25 General Standards for Aerospace and Propulsion Systems
  • Aerospace Standard
  • MA3279D
  • Current
Published 2019-02-26 by SAE International in United States
No Abstract Available.
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