Design of Optimum Torsionally Flexible PropRotors for Tilt-Body MAVs

This paper presents a methodology to design the optimum proprotor for tilt-body microair-vehicles (TB-MAV) with efficient global propulsion system and long flight endurance in both cruise and hover modes. The TB-MAV developed at ISAE, which is called MAVion, was used as a baseline in the design process. To acquire maximum performance of TB-MAV’s global propulsion system, an efficient optimization process of the proprotor propulsion system was carried out. The optimization process consists of two-step inverse design methods. The first step determines the optimal operating conditions in terms of power and rotational speed of proprotor and the second step designs the optimal blade geometry in terms of twist angle distribution. The optimal blade twist distribution along the blade was computed using the Glauert’s strip theory for minimum energy loss condition. Meanwhile, the optimal operating conditions were determined by the motor outputs corresponding to high motor efficiency. A comparison of performance in terms of total efficiency and flight endurance between the optimized flexible proprotor, the optimized rigid proprotor, optimized propeller and optimized rotor is presented

Traffic light dispersion control based on deep reinforcement learning

The current traffic light controls are ineffective and causes a handful of problems such as congestion and pollution. This study investigates the application of deep reinforcement learning on traffic control systems to minimize congestion at traffic intersection. The traffic data from Pulai Perdana, Skudai, Johor Intersection was extracted, analysed and simulated based on the Poisson Distribution, using a simulator, Simulation of Urban Mobility (SUMO). In this research, we proposed a deep reinforcement learning model, which combines the capabilities of convolutional neural networks and reinforcement learning to control the traffic lights to increase the effectiveness of the traffic control system. The paper explains the method we used to quantify the traffic scenario into different matrices which fed to the model as states which reduces the load of computing as compared to images. After 2000 iterations of training, our deep reinforcement learning model was able to reduce the cumulative waiting time of all the vehicles at the Pulai Perdana intersection by 47.31% as compared to a fixed time algorithm and can perform even when the traffic is skewed in a different direction. When the traffic is scaled down to 50% and 20 %, the agent continues to improve the waiting time by 69.5% and 68.36 % respectively. It is proven in the experiment that a deep reinforcement learning model was able to reduce the cumulative waiting time at Pulai Perdana by 47.31%

Study of a Flexible UAV Proprotor

This paper is concerned with the evaluation of design techniques, both for the propulsive performance and for the structural behavior of a composite flexible proprotor. A numerical model was developed using a combination of aerodynamic model based on Blade Element Momentum Theory (BEMT), and structural model based on anisotropic beam finite element, in order to evaluate the coupled structural and the aerodynamic characteristics of the deformable proprotor blade. The numerical model was then validated by means of static performance measurements and shape reconstruction from Laser Distance Sensor (LDS) outputs. From the validation results of both aerodynamic and structural model, it can be concluded that the numerical approach developed by the authors is valid as a reliable tool for designing and analyzing the UAV-sized proprotor made of composite material. The proposed experiment technique is also capable of providing a predictive and reliable data in blade geometry and performance for rotor modes

Effectiveness of blade tip on low speed horizontal axis wind turbine performance

There has been an increasing demand for renewable energy in order to create a sustainable society as the non-renewable energies such as fossil fuel resources are limited. Modern wind turbines claim that they have a high efficiency in term of wind energy extraction. However, there are still having losses due to tip vortex causing to a reduction in performance. Motivated by this reason, this research aims at exploring the possibility to increase the performance of low speed small-scaled horizontal axis wind turbine with various tip devices using Computational Fluid Dynamics (CFD). Four wind turbine blades with different tip devices which consist of sword tip, swept tip, upwind winglet and downwind winglet are compared with wind turbine blade without tip device in term of CP. The application of tip device can significantly reduce induced tip vortex and improve wind turbine performance. For TSR below than 4, adding a sword tip increases CP about 7.3%, swept tip increases CP about 9.1%, upwind winglet increases CP about 1.8% and downwind winglet increases CP about 3.2%. It is observed that the best tip device for low wind speed application is swept tip as it give the highest performance increment compared to without tip device

Performance improvement of small-scale rotors by passive blade twist control

A passive twist control is proposed as an adaptive way to maximize the overall efficiency of the small-scale rotor blade for multifunctional aircrafts. Incorporated into a database of airfoil characteristics, Blade Element Momentum Theory is implemented to obtain the blade optimum twist rates for hover and forward flight. In order to realize the required torsion of blade between hover and forward flight, glass/epoxy laminate blade is proposed based on Centrifugal Force Induced Twist concept. Tip mass is used to improve the nose-down torsion and the stabilization of rotating flexible blade. The laminate blades are tested in hover and forward flight modes, with deformations measured by Laser Displacement Sensor. Two Laser Displacement Sensors are driven by the tracking systems to scan the rotating blade from root to tip. The distance from blade surface to a reference plane can be recorded section by section. Then, a polynomial surface fitting is applied to reconstruct the shape of rotating blade, including the analysis of measurement precision based on the Kline–McClintock method. The results from deformation testings show that nose-down torsion is generated in each flight mode. The data from a Fluid Structure Interaction model agrees well with experimental results at an acceptable level in terms of the trend predictions

Performance Enhancement of Tilt-Body Micro Air Vehicle by Use of Orthotropic Laminated Proprotors

A passive twist control is considered as an adaptive way to maximize the overall efficiency of a proprotor developed for convertible Micro Air Vehicles (MAV). In this paper, adaptation of the proprotor geometry in accordance to flight configurations is achieved by induced twist generated by the inherent structural coupling effect in anisotropic composite material and centrifugal force emanating from the tip load. Beam Finite Element Model based on Rotating Timoshenko Theory is used to predict structural loads, while Blade Element Momentum Theory is employed to predict the aerodynamic performance of adaptive proprotor as applied on Micro Air Vehicles (MAV). The iterative process of combination of aerodynamic model and structural model is used to compute the steady-state deformation of the flexible laminated proprotor blade due aerodynamic loads. Finally, the optimal design of lamina blade material is carried out to investigate the potential of flexible blade in the proprotorperformance enhancement

Clean room performance testing in hospital's vascular interventional radiology laboratory

A Vascular Interventional Radiology (VIR) laboratory is a hospital facility that requires clean room standards to reduce infection risks. In the VIR laboratory, laparoscopic surgery, known as minimally invasive surgery, is performed with the use of video imaging. This article describes a standard practice of conducting field measurements in an ISO Class 8 VIR laboratory. The measurements were carried out at rest conditions as described in ISO 14644-1 standard. The lab was equipped with High-Efficiency Particulate Air (HEPA) filters, and a vertically downward unidirectional flow system. A TSI 9310-02 airborne particle counter was used to measure three different particle sizes, namely, PM 0.5, PM 1.0 and PM 5.0. Meanwhile, an Alnor EBT 731 manometer was utilised to measure the average airflow velocity and pressure differential. On average, the recorded values of PM 0.5, PM 1.0 and PM 5.0 concentrations are 923351 particles/m3, 56963 particles/m3, and 551 particles/m3, respectively. While, the average measured values of supply air velocity, pressure differential, air temperature and relative humidity are 0.43 m/s, +0.79 Pa, 20.5ºC, and 63.3% respectively. This study shows that all the measured parameters are within the threshold values prescribed in the ISO Class 8 standard

Study of A Flexible Blade for Optimized Proprotor

In the present study, a passive twist control is considered as a potential way to improve the overall flight efficiency for proprotor of Micro Air Vehicle (MAV). This paper will focus on the aerodynamic performance and deformation behaviour of a flexible laminate blade. Incorporated with a database of airfoil characteristics, Blade Element Momentum Theory (BEMT) is implemented for performance prediction of proprotor at low Reynolds numbers. The preliminary procedure is based on finding optimum twist distributions for hover and forward flight, but keeping a given chord distribution. A numerical model is developed using a combination of aerodynamic model based on BEMT, and structural model based on anisotropic beam finite element, in order to evaluate the coupled structural and the aerodynamic characteristics of the deformable proprotor blade. The numerical model - Fluid Structure Interaction (FSI) was then validated by means of shape reconstruction from LDS (Laser Displacement Sensor) outputs. It can be concluded that the proposed experiment technique is capable of providing a predictive and reliable data in blade geometry and performance for rotor mode. The FSI approach is also valid as a reliable tool for designing and analyzing the MAV proprotor made of composite material

The evaluation of drag and lift force of groove cylinder in wind tunnel

Cylindrical structures subjected to flow are widely used in marine and offshore engineering and in structural applications. It has been shown that circular cylinder surface modifications can affect the separation point to move backward on the cylinder surface. Thus, reducing the drag coefficient. Flow past a circular cylinder with smooth, half and full rectangular, grooved surfaces (roughness coefficient k/D=0.04) were investigated in a low-speed open ended wind tunnel. The outer diameters (D) of the cylinders were 50mm and the depths (k) of the grooves were 2mm. The Reynold's number ranged from 1.65x104 to 1.13x105. The drag and lift coefficients of the cylinders were measured using a three-component balance. The wake flow patterns of the cylinders were observed using a smoke visualization technique. The results show that the full grooves and half grooves facing the flow produced a lower drag than a smooth cylinder with a half groove located at the leeside of the flow. The full grooved cylinder showed a drag reduction of 55% at Re=1x105. The presence of the groove on the cylinder's surface tripped the boundary layer and showed a smaller and narrower wake than a smooth cylinder

Numerical and experimental study on flexible blade for tilt-body drones

This paper is concerned with the evaluation of design techniques, both for the propulsive performance and for the structural behavior of a composite flexible proprotor. A numerical model was developed using a combination of aerodynamic model based on Blade Element Momentum Theory (BEMT), and structural model based on anisotropic beam finite element, in order to evaluate the coupled structural and the aerodynamic characteristics of the deformable proprotor blade. The numerical model was then validated by means of static performance measurements and shape reconstruction from Laser Distance Sensor (LDS) outputs. From the validation results of both aerodynamic and structural model, it can be concluded that the numerical approach developed by the authors is valid as a reliable tool for designing and analyzing the drone proprotor made of composite material. The proposed experiment technique is also capable of providing a predictive and reliable data in blade geometry and performance for rotor modes. Mots clefs