scholarly journals Aerodynamic Optimization of a Micro Quadrotor Aircraft with Different Rotor Spacings in Hover

2020 ◽  
Vol 10 (4) ◽  
pp. 1272 ◽  
Author(s):  
Yao Lei ◽  
Hengda Wang
Keyword(s):  
Numerical Simulations ◽  
Negative Impact ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Aerodynamic Optimization ◽  
Quadrotor Aircraft ◽  
Blade Tip ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Interference ◽  
Cfd Method

In order to study the aerodynamic performance of the quadrotor with different rotor spacings in hover, experiments were performed together with numerical simulations. For experimental study, an experimental platform was designed to measure the thrust and power consumption of the quadrotor with different rotor spacings (L/R = 2.2, 2.6, 3.0, 3.2, 3.6, and 4.0), and to attempt to find out the optimal rotor configuration which makes the quadrotor have the best aerodynamic performance. In addition, the pressure distribution, vorticity of the blade tip, and velocity vector of quadrotor in the flow field were obtained by Computational Fluid Dynamics (CFD) method to visually analyze the aerodynamic interference between adjacent rotors. By the comparison of experimental results and numerical simulations, the final results show that the aerodynamic performance of the quadrotor varies obviously with the change of rotor spacing, and it has a negative impact on hover efficiency if rotor spacing is too much small or large. The rotors pacing at L/R = 3.6 with larger thrust and smaller power is considered to be the best aerodynamic configuration for the quadrotor with better aerodynamic characteristics. Furthermore, compared with the isolated rotor, moderate aerodynamic interference is proved to help improve the aerodynamic performance of the quadrotor with a larger thrust, especially for a rotor spacing at L/R = 3.6.

scholarly journals Aerodynamic Characteristics of a Micro Multi-Rotor Aircraft with 12 Rotors Considering the Horizontal Wind Disturbance

2020 ◽  
Vol 10 (20) ◽  
pp. 7387
Author(s):  
Yao Lei ◽  
Wenjie Yang ◽  
Hengda Wang
Keyword(s):  
Power Consumption ◽  
Micro Air Vehicles ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Horizontal Wind ◽  
Wind Disturbance ◽  
Wind Speeds ◽  
Hover Performance ◽  
Blade Tip ◽  
Cfd Method

Wind disturbance posed difficulties for the stability of the micro air vehicles (MAVs) with attitude variation. In this paper, the aerodynamic performance of a MAV with six coaxial rotor pairs considering the horizontal wind is investigated by both experiments and numerical simulations. First, the effect of the horizontal wind on the multi-rotor aircraft is analyzed in detail. Then, low-speed wind tunnel tests were performed to obtain the thrust and power consumption and the aerodynamic performance of the multi-rotor aircraft (l/D = 1.2 and h/D = 0.19) with the rotational speed of 1500–2300 r/min in the horizontal wind ranged from 0 to 5 m/s. Finally, the distribution of streamline, the pressure of the blade tip, and the velocity and the vortices in the flow field of a multi-rotor aircraft with horizontal wind disturbance, were simulated and studied using the computational fluid dynamics (CFD) method. Through the comparison of experimental results and simulation results, it can be seen that the horizontal wind disturbance will increase power consumption to weaken the aerodynamic performance at higher rotor speeds. However, larger thrust and better hover performance are obtained at lower rotational speeds with good wind resistance. Additionally, due to the mutual induction between rotor wakes, the interactions of downwash flows become more intense at higher rotational speeds or larger wind speeds where the vortexes at the blade tip deformed and moved along with the wind.

URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

2017 ◽  
Author(s):  
Gi-Don Na ◽  
Frank Kameier ◽  
Nils Springer ◽  
Michael Mauß ◽  
C. O. Paschereit
Keyword(s):  
Applied Sciences ◽  
Numerical Simulations ◽  
Aerodynamic Performance ◽  
Design Parameters ◽  
Experimental Investigations ◽  
Acoustic Measurements ◽  
Noise Emission ◽  
Industrial Partner ◽  
University Of Applied Sciences ◽  
Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

scholarly journals Aerodynamic Analysis of a Flapping Wing Aircraft for Short Landing

2020 ◽  
Vol 10 (10) ◽  
pp. 3404
Author(s):  
Bing Ji ◽  
Zenggang Zhu ◽  
Shijun Guo ◽  
Si Chen ◽  
Qiaolin Zhu ◽  
...  
Keyword(s):  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Aerodynamic Analysis ◽  
Drag Forces ◽  
Wing Model ◽  
Aerodynamic Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Difference ◽  
Cfd Method ◽  
Lift And Drag

An investigation into the aerodynamic characteristics has been presented for a bio-inspired flapping wing aircraft. Firstly, a mechanism has been developed to transform the usual rotation powered by a motor to a combined flapping and pitching motion of the flapping wing. Secondly, an experimental model of the flapping wing aircraft has been built and tested to measure the motion and aerodynamic forces produced by the flapping wing. Thirdly, aerodynamic analysis is carried out based on the measured motion of the flapping wing model using an unsteady aerodynamic model (UAM) and validated by a computational fluid dynamics (CFD) method. The difference of the average lift force between the UAM and CFD method is 1.3%, and the difference between the UAM and experimental results is 18%. In addition, a parametric study is carried out by employing the UAM method to analyze the effect of variations of the pitching angle on the aerodynamic lift and drag forces. According to the study, the pitching amplitude for maximum lift is in the range of 60°~70° as the flight velocity decreases from 5 m/s to 1 m/s during landing.

Influence Mechanisms of Manufacture Variations on Supersonic/Transonic Blade Aerodynamic Performances

2020 ◽  
Author(s):  
Baojie Liu ◽  
Jiaxin Liu ◽  
Xianjun Yu ◽  
Dejun Meng ◽  
Wenbin Shi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Statistical Analysis ◽  
Mach Number ◽  
Systematic Errors ◽  
Aerodynamic Performance ◽  
Aerodynamic Performances ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Abstract The results of previous studies have proved that manufacture variations can cause a noticeable influence on compressor aerodynamic performance. The main objective of this paper is to investigate the influence rules and mechanisms of manufacture variations on supersonic/transonic blades aerodynamic performance. The variations used in this study were measured from some newly manufactured high-pressure compressors. In the present study, several blade sections with different design Mach number conditions are selected for further statistical analysis of measured deviation data. Therefore, some systematic errors in the deviation data have been revealed. Based on these data, the computational fluid dynamics (CFD) method has been used to obtain the aerodynamic performances of a large number of the measured blade elements. And then, the analysis of the influence rules of manufacture variations on blade aerodynamic performance in different Mach number conditions has been carried out. The present results indicate that the effects of manufacture variations on blade aerodynamic performance in the lower Mach number (0.8) condition are much more significant comparing to that in the higher Mach number (0.9∼1.2) conditions. Based on this, influence mechanisms of manufacture variations on positive incidence range and negative incidence range have been analyzed. The differences of influence mechanisms in different Mach number conditions are the focus of research.

scholarly journals Effects of Wind Disturbance on the Aerodynamic Performance of a Quadrotor MAV during Hovering

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Yao Lei ◽  
Yiyong Huang ◽  
Hengda Wang
Keyword(s):  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Vertical Wind ◽  
Horizontal Wind ◽  
Wind Disturbance ◽  
Power Variation ◽  
Quadrotor Aircraft ◽  
Spacing Ratio ◽  
Power Loading ◽  
Vertical Winds

Wind disturbance could render thrust and power variation or even causing roll which is difficult to maintain a steady flight in gust especially when the horizontal or vertical wind is involved. In this paper, the horizontal wind and vertical wind are presented to study the influence of wind disturbance on aerodynamic characteristics of the quadrotor aircraft in hovering by experiments and numerical simulations. First, the simplified aerodynamic model with the wind disturbance was analyzed in detail. Also, the low-speed wind tunnel tests were performed to obtain the thrust and power variation of the quadrotor aircraft with rotor spacing ratio s = 1.1 -1.8 in both horizontal and vertical winds of 0-5 m/s with the rotational speed ranging from 1500 to 2300 rpm. Finally, the simulations are performed by utilizing the Computational Fluid Dynamics (CFD) software ANSYS to study the flow field distribution of quadrotor with the influence of the wind disturbance. The comparison between experimental results and simulation results shows that the quadrotor achieves better aerodynamic performance with larger thrust and smaller power consumption at rotor spacing ratio s = 1.8 . Additionally, the quadrotor can effectively resist the horizontal wind disturbance, which will bring larger power loading for the quadrotor, especially at 2.5 m/s. However, the vortices near blade-tip move upwards and deform with the influence of vertical wind, resulting in the reduction of thrust and aerodynamic performance of the quadrotor.

scholarly journals Research on the Water Ridge and Slamming Characteristics of a Semisubmersible Platform under Towing Conditions

2022 ◽  
Vol 10 (1) ◽  
pp. 116
Author(s):  
Fali Huo ◽  
Changdong Wei ◽  
Chenyang Zhu ◽  
Zhaojun Yuan ◽  
Sheng Xu
Keyword(s):  
Numerical Simulations ◽  
Wave Height ◽  
Experimental Tests ◽  
Linear Increase ◽  
Wave Period ◽  
Wave Slamming ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Rough Sea ◽  
Pressure Analysis

During the towing of semisubmersible platforms, waves impact and superpose in front of the platform to form a ridge shaped “water ridge”, which protrudes near the platform and produces a large slamming pressure. The water ridges occur frequently in the towing conditions of semisubmersible platforms. The wave–slamming on the braces and columns of platform is aggravated due to the water ridges, particularly in rough sea conditions. The effect of water ridges is usually ignored in slamming pressure analysis, which is used to check the structural strengths of the braces and columns. In this paper, the characteristics of the water ridge at the braces of a semisubmersible platform are studied by experimental tests and numerical simulations. In addition, the sensitivity of the water ridge to the wave height and period is studied. The numerical simulations are conducted by a Computational Fluid Dynamics (CFD) method, and their accuracy is validated based on experimental tests. The characteristics of the water ridge and slamming pressure on the braces and columns are studied in different wave conditions based on the validated numerical model. It is found that the wave extrusion is the main reason of water ridge. The wave–slamming pressure caused by the water ridge has an approximately linear increase with the wave height and is sensitive to the wave period. With the increase of the wave period, the wave–slamming pressure on the brace and column of the platform increases first and then decreases. The maximum wave–slamming pressure is found when the wave period is 10 s and the slamming pressure reduces rapidly with an increase of wave period.

scholarly journals Numerical Investigation on Aerodynamic Characteristics of Damaged Infinite Wings With Variation in Penetration Angle

2020 ◽  
Author(s):  
Bahareh Yahyavi ◽  
Mahmoud Mani ◽  
Habibollah Naddaf
Keyword(s):  
Negative Impact ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Performance ◽  
Hole Diameter ◽  
Pitching Moment ◽  
Surface Pressure Distribution ◽  
Moment Coefficient ◽  
Pass Through ◽  
Good Agreement

Aerodynamic performance of a full span NACA 641-412 airfoil with a circular-shaped damage at various attack directions has been numerically investigated in this study. To assess the aerodynamic effects of different penetration angles in which threats such as projectiles can pass through the wings, attack directions of 30°, 60°, -30° and -60° relative to the normal axis of the chord line has been studied and compared with attack direction of 0°. To validate with published studies about damaged wing, the 200 mm chord airfoil was simulated with the damage hole diameter of 20% chord at the midspan and midchord location in Reynolds number of 500,000. Quantitative and qualitative results of this numerical study had a good agreement with published experimental data due to appropriate structured mesh and turbulence modelling. In addition to lift, drag and pitching moment coefficient, surface pressure distribution around the damage hole has been studied. Results show that, if the penetration angle becomes more negative, aerodynamics performance of the wing will be further decreased; therefore, attack directions of threat mechanisms such as “ahead and above” or “below from the rear” have severe negative impact than other directions on aerodynamic performance of the damaged infinite wing.

scholarly journals Aerodynamic Performance of an Octorotor SUAV with Different Rotor Spacing in Hover

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1364
Author(s):  
Yao Lei ◽  
Yuhui Huang ◽  
Hengda Wang
Keyword(s):  
Flow Field ◽  
Unmanned Aerial Vehicles ◽  
Aerodynamic Performance ◽  
Aerodynamic Efficiency ◽  
Experimental Platform ◽  
Vorticity Distribution ◽  
Aerial Vehicles ◽  
Spacing Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

To study the aerodynamic performance of hovering octorotor small unmanned aerial vehicles (SUAV) with different rotor spacing, the computational fluid dynamics (CFD) method is applied to analyze the flow field of an octorotor SUAV in detail. In addition, an experimental platform is built to measure the thrust and power of the rotors with rotor spacing ratios L/D of 1.0, 1.2, 1.4, 1.6, and 1.8, sequentially. According to the theory of momentum, rotor aerodynamic performance is obtained with qualitative analysis. Further analysis with numerical simulation is presented with the flow field of the octorotor SUAV, the vorticity distribution, velocity distribution, pressure distribution, and streamline. The results show that the aerodynamic performance varies with the rotor spacing. Specifically, the aerodynamic performance is poor at L/D = 1.0, which is accompanied with strong interaction of wake and tip vortexes and interaction with each other. However, the aerodynamic efficiency is much improved with a larger rotor spacing, especially achieving the highest at L/D = 1.8, which is considered to be the best rotor spacing ratio for this kind of octorotor SUAV.

Aerodynamic optimization of wind turbine rotor using CFD/AD method

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840053 ◽  
Author(s):  
Jiufa Cao ◽  
Weijun Zhu ◽  
Tongguang Wang ◽  
Shitang Ke
Keyword(s):  
Wind Turbine ◽  
Fluid Dynamic ◽  
Computational Cost ◽  
Turbine Rotor ◽  
Aerodynamic Performance ◽  
Aerodynamic Optimization ◽  
Turbine Rotor Blade ◽  
Design And Optimization ◽  
Cfd Method ◽  
Wind Turbine Rotor

The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier–Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.

scholarly journals Optimization of aerodynamic performance for co-axial rotors with different rotor spacings

2018 ◽  
Vol 10 (4) ◽  
pp. 362-369
Author(s):  
Yao Lei ◽  
Yuxia Ji ◽  
Changwei Wang
Keyword(s):  
Power Consumption ◽  
Aerodynamic Performance ◽  
Separation Distance ◽  
Power Coefficient ◽  
Axial Thrust ◽  
Thrust Coefficient ◽  
Hover Performance ◽  
Power Loading ◽  
Blade Tip ◽  
Aerodynamic Interference

In this article, attempts are made to study the aerodynamic performance of co-axial rotors with different rotor spacings in hover. A custom-designed experimental platform with seven rotor spacings ( z/D = 0.16, 0.19, 0.23, 0.26, 0.29, 0.33 and 0.38) is applied to measure the hover performance, i.e. co-axial thrust and power consumption, and to optimize the aerodynamic configuration of the co-axial system. The experimental errors in thrust coefficient, power coefficient and power loading calculated through ‘Kline-McClintock equation’ are less than 2%. Additionally, the streamline distribution and pressure of blade tip at different rotor spacings obtained from numerical simulations are presented to visualize the effects of aerodynamic interference between the top and bottom rotor. Results show that the aerodynamic performance of a co-axial rotor with the specific rotor configure and speed range can be indeed improved by changing the rotor spacing, and the optimal performance is obtained with a rotor spacing of 0.19. Also, the magnitude of aerodynamic interference related to the axial separation distance has demonstrated to be beneficial on the total thrust and power consumption. For the same disc loading, a decrease in rotational speed results in an increase in power loading especially for z/D = 0.19. It is also found that the bottom rotor does affect the performance of the top rotor at smaller rotor spacings, whereas the effect is significantly reduced as the rotor spacing increases.

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