Experimental assessment of the noise characteristics of propellers for commercial drones

2021 ◽  
Vol 263 (2) ◽  
pp. 4418-4425
Author(s):  
Han Wu ◽  
Peng Zhou ◽  
Siyang Zhong ◽  
Xin Zhang ◽  
Kunyu Luo
Keyword(s):  
Low Cost ◽  
Industrial Applications ◽  
Broadband Noise ◽  
Small Scale ◽  
Noise Emission ◽  
Rotor Aerodynamics ◽  
Noise Characteristics ◽  
Wide Range ◽  
Test Platform ◽  
The Status

Multi-copters or drones are engaged in a wide range of industrial applications for their flexibility, safety and low-cost. The noise emission is becoming an issue with the expanding applications, among which the propellers that drive the drones are the major sources of noise. In this work, the noise characteristics of small-scale propellers is experimentally investigated using the advanced rotor aerodynamics and aeroacoustics test platform in an anechoic chamber at the Hong Kong University of Science and Technology (HKUST). The study will focus on the representative off-the-shelf propellers. The rotor noise will be measured by a linear array with 20 microphones, and the aerodynamic forces will be acquired by using the high-accuracy load cells. The dependence of both the tonal and broadband noise radiation with the thrust and rotation speed at various conditions will be tested. The study will enhance our understanding of the noise features of the multi-rotor powered drones, and will provide us with a better understanding of the status of the drone noise impact on the environment.

scholarly journals Noise of small-scale contra rotating rotors

2021 ◽  
Vol 2061 (1) ◽  
pp. 012019
Author(s):  
I P Boychuk ◽  
A V Grinek
Keyword(s):  
Experimental Study ◽  
Rotor Blade ◽  
Filling Factor ◽  
Broadband Noise ◽  
Small Scale ◽  
Noise Levels ◽  
Noise Emission ◽  
Aerodynamic Loads ◽  
Noise Characteristics ◽  
Soundproof Chamber

Abstract This article presents the results of an experimental study of the noise characteristics of small-scale coaxial counter-rotating rotors. The tests were carried out in an anechoic soundproof chamber for F7/A7 counter-rotating rotors with 11 and 9 blades on the front and rear rotors, respectively. The intensity of noise emission by rotors was compared with the constancy of the thrust of the power units. Acoustic studies have shown the presence of tonal and broadband noise components at low rotation speeds. In addition to the usual noise components, tonal components were also observed for the rotor blade running combinations. The observed noise levels at these frequencies are equal, and in some directions are significantly higher than the noise levels at the frequencies of the blades of the first and second rows. In experiments, it was found that, while maintaining the equality of the rods, with an increase in the diameter, the noise levels at the rotors decrease due to a decrease in peripheral speeds. A decrease in the noise levels of rotors with an increase in the number of blades was established due to a decrease in aerodynamic loads on the blades and peripheral speeds. An important parameter here is the filling factor of the space swept by the blades. With an increase in this coefficient, the rotation noise decreases, but the vortex noise increases significantly.

Low cost Real Time Centralized Speed Control of DC Motor Using Lab view -NI USB 6008

2016 ◽  
Vol 7 (3) ◽  
pp. 656 ◽  
Author(s):  
C. Bharatiraj ◽  
JL Munda ◽  
Ishan Vaghasia ◽  
Rajesh Valiveti ◽  
P. Manasa
Keyword(s):  
Virtual Instrument ◽  
Low Cost ◽  
Speed Control ◽  
Dc Motor ◽  
Industrial Applications ◽  
Laboratory Model ◽  
Small Scale ◽  
Motor Speed ◽  
Software Environment ◽  
Lab View

The DC motors an outstanding portion of apparatus in automotive and automation industrial applications requiring variable speed and load characteristics due to its ease of controllability. Creating an interface control system for multi DC motor drive operations with centralized speed control, from small-scale models to large industrial applications much demand. By using Lab VIEW (laboratory virtual instrument engineering workbench) as the motor controller, can control a DC motor for multiple purposes using single software environment. The aim of this paper is to propose the centralized speed control of DC motor using Lab VIEW. Here, the Lab VIEW is used for simulating the motor, whereas the input armature voltage of the DC motor is controlled using a virtual Knob in Lab VIEW software. The hardware part of the system (DC motor) and the software (in personal computer) are interfaced using a data acquisition card (DAQ) -Model PCI- 6024E. The voltage and Speed response is obtained using LABVIEW software. Using this software, group of motors’ speed can be controlled from different location using remote telemetry. The propose work also focuses on controlling the speed of the individual DC motor using PWM scheme (Duty cycle based Square wave generation) and DAQ. Help of the DAQ along with Lab VIEW front panel window, the DC motor speed and directions can be change easily in remote way. In order to test the proposed system the laboratory model for an 80W DC motor group (multi drive) is developed for different angular displacements and directions of the motor. The simulation model and experimental results conforms the advantages and robustness of the proposed centralized speed control.

High Power Gyrotrons

1994 ◽  
Vol 347 ◽  
Author(s):  
R. J. Temkin ◽  
K. E. Kreischer
Keyword(s):  
High Power ◽  
Plasma Heating ◽  
Industrial Applications ◽  
Continuous Operation ◽  
Materials Processing ◽  
Pulse Operation ◽  
Wide Range ◽  
Magnetically Confined ◽  
The Status ◽  
Long Pulse

ABSTRACTHigh power gyrotrons have been developed for application to plasma heating in the program of magnetically confined nuclear fusion research. Gyrotron power levels of up to 1 MW in long pulse operation (>ls) and up to 200 kW in true continuous operation (CW) have been demonstrated at frequencies in the 8 to 140 GHz range. The status of high power gyrotron development is reviewed. One current goal of the worldwide gyrotron effort is the development of 1 MW,CW gyrotrons at a frequency of about 170 GHz for heating the proposed international tokamak ITER to ignition. Gyrotrons are also now being used in a variety of other applications including materials processing. Improved gyrotrons with features such as wide range tuning could be developed for industrial applications.

scholarly journals Reducing post-harvest losses in fruits and vegetables for ensuring food security – Case of Sri Lanka

2021 ◽  
Vol 9 (1) ◽  
pp. 7-16
Author(s):  
Leelananda Rajapaksha ◽  
DMC Champathi Gunathilake ◽  
SM Pathirana ◽  
TN Fernando
Keyword(s):  
Food Security ◽  
Sri Lanka ◽  
Urban Areas ◽  
Low Cost ◽  
Economic Benefits ◽  
Fruit And Vegetables ◽  
Cold Chain ◽  
Small Scale ◽  
Post Harvest ◽  
Wide Range

In Sri Lanka, 70% of 21 million population live in non-urban areas, and agriculture provides livelihood for approximately 40% of them. The agricultural marketing process in the country is a complex operation due to services and functions involved in moving a crop product from where it was produced to where it would finally be consumed. Further, with a wide range of agricultural crops being produced, post-harvest handling process create different degrees of quantitative and qualitative losses in a complex market chain, which are estimated at 20% to 40% for vegetables and 30% - 40% for fruits. Improper and non-scientific post-harvest practices and handling, gaps in integration of cold chain practices & elements with post-harvest process, and lack of knowledge & awareness on many related aspects at grass root farmer level etc. appear to contribute to losses that finally prevent due economic benefits reaching the small-scale producer. In order to increase the effectiveness of post-harvest process handling of fruit and vegetables, appropriate corrective measures targeting small scale producers as well as commercial scale producers need to be popularized and practiced. At small scale producer level, promotion of appropriate low-cost post-harvest practices and procedures, facilitating low-cost cold chain elements and user-friendly information flow mechanism on market situation would certainly help avoid some of the steps that lead to losses. Monitoring system of commercial post-harvest handling process that ensure scientific bulk handling, storage and transportation of fruit and vegetables, properly designed economic centers with well regulated environmentcontrolled storages etc. would greatly reduce loses in bulk handling, ensuring better food security in the island.

scholarly journals Advanced Wireless Sensor Networks for Sustainable Buildings Using Building Ducts

2018 ◽  
Vol 10 (8) ◽  
pp. 2628
Author(s):  
Heekwon Yang ◽  
Byeol Kim ◽  
Joosung Lee ◽  
Yonghan Ahn ◽  
Chankil Lee
Keyword(s):  
Wireless Sensor Networks ◽  
Sensor Networks ◽  
Network Performance ◽  
Low Cost ◽  
Industrial Applications ◽  
Wireless Sensor ◽  
Packet Error Rate ◽  
Existing Building ◽  
Transmission Delays ◽  
Wide Range

The communication technology ZigBee has been widely adopted in wireless sensor networks (WSNs) for a wide range of industrial applications. However, although ZigBee provides low-power, low-cost mesh networking, it cannot guarantee steady and predictable network performance as channels are time-variant and highly attenuated by man-made obstacles. The networks also suffer from interference, especially in the important 2.4 GHz industrial, scientific, and medical (ISM) band. These degraded channel characteristics increase the number of hops, thus increasing both the packet error rate and transmission delays. In this paper, we report the deployment of a ZigBee-based WSN inside an existing building duct system utilized for intelligent waste collection in an industrial environment. The Received Signal Strength (RSS) and path losses were measured, revealing that the duct communication channel acts as a very effective waveguide, providing a more reliable and consistent network performance than conventional free space channels.

Investigation of Wear Behaviour ZA 27 Using Bio-Lubricants

2014 ◽  
Vol 550 ◽  
pp. 21-29
Author(s):  
M. Samuel Gemsprim ◽  
N. Babu ◽  
S. Parimala Murugaveni ◽  
P.R. Thyla
Keyword(s):  
Journal Bearing ◽  
Low Cost ◽  
Industrial Applications ◽  
Wear Behaviour ◽  
Base Oil ◽  
Wide Range ◽  
Milling Machines ◽  
Pin On Disc ◽  
Bearing Materials ◽  
Sliding Distance

— The Zinc–Aluminium (ZA) family of casting alloys are gaining wide commercial importance as journal bearing material for high load and low speed applications. These alloys, most notably ZA-27 is capable of replacing traditional bronze bearing at low cost. Recently, the ZA-27 alloy has been substituted for conventional journal bearing materials in a wide range of industrial applications. The journal bearings produced from these alloys have been used in earthmoving equipments, mining and milling machines, cable winches and compressors. The ZA-27 alloys and the bearings were also used in heavy and dusty environments such as underground machines, ore crashers and rock drills.The tribological properties of the ZA 27 alloy were tested using a Pin-on-Disc friction and wear tribotester.Sliding wear tests were performed using the tribotester by varying load, speed & sliding distance. The same tests are done with lubricating condition and also with bio lubricants. The Bio-lubrication is adopted in this work because of its biodegradability and eco-friendly nature. Especially the soya bean oil possess good lubrication properties. The wear rate of dry, base oil and bio lubricant oil condition were determined different applied load, speed and sliding distance compared with each other.

scholarly journals Pressures and Status of Seagrass Ecosystem in the Coastal Areas of North Bintan, Indonesia

2018 ◽  
Vol 47 ◽  
pp. 04008
Author(s):  
Ita Karlina ◽  
Fery Kurniawan ◽  
Fadhliyah Idris
Keyword(s):  
Coastal Areas ◽  
Coastal Development ◽  
Small Scale ◽  
Anthropogenic Pressures ◽  
Conservation Area ◽  
Seagrass Meadows ◽  
Seagrass Ecosystem ◽  
Wide Range ◽  
Sea Grass ◽  
The Status

This study investigates the status and anthropogenic pressures on seagrass ecosystem. Urbanization and tourism in the coastal areas of Bintan, Indonesia were increasing in the recent years. They have become new pressures to intertidal ecosystem and habitats, particularly seagrass ecosystem. Seagrass meadows are the important ecosystem and habitats in Bintan region. They provide a wide range of ecosystem services, including for small-scale fisheries and have being Dugongs (Dugong dugon) habitats for food. Currently, the sea grass status is less healthy or damaged with 11 species. The anthropogenic disturbance processes have affected the spatial distribution, percent coverage, biodiversity, and community structure of sea grass. Moreover, several species are hard to find. Directly, sea grass meadows are impacted by introduced coastal development (i.e. settlement area, tourism accommodation, port, etc.), land-based pollution, reclamation, boating traffic, dredging activities and tourism activities. Sea grass conservation area and marine spatial planning based on the land- and seascape connectivity is important for conservation efforts and sustainable management of sea grass.

scholarly journals Low-Cost Synthesis and Characterization of Silver Nanoparticles for Diverse Sensing Application

2019 ◽  
Vol 9 (2) ◽  
pp. 3915-3917
Author(s):  
S. Akhtar ◽  
Z. Farid ◽  
H. Ahmed ◽  
S. A. Khan ◽  
Z. N. Khan
Keyword(s):  
Silver Nanoparticles ◽  
Chemical Reduction ◽  
Low Cost ◽  
Industrial Applications ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
X Ray ◽  
Wide Range ◽  
Range Of Functions

Silver (Ag) nanoparticles (NPs) are synthesized and characterized by a low-cost chemical reduction method. Silver nanoparticles (Ag NPs) have pre-occupied the consideration of the scientific community due to their wide range of functions, utility and industrial applications, particularly in the fields of sensing technologies and medicine (particularly their efficiency against microbes, the ability of healing the wound and anti-inflammatory properties). Ag NPs are synthesized by a low-cost fabrication method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray diffraction (EDX) and photometry techniques are used in this work to identify their nature and potentiality for diverse applications in sensing technologies.

scholarly journals Experimental studies of single rotors noise of small scale

2021 ◽  
Vol 2061 (1) ◽  
pp. 012040
Author(s):  
IP Boychuk ◽  
AV Grinek
Keyword(s):  
Electric Motor ◽  
Rotational Speed ◽  
Experimental Studies ◽  
Small Diameter ◽  
Broadband Noise ◽  
Small Scale ◽  
Brushless Motors ◽  
Higher Harmonics ◽  
Noise Characteristics ◽  
Mechanical Noise

Abstract The work experimentally investigated the characteristics of the noise of large-scale isolated rotors on small-scale models. The experimental rotor model was based on the F7 / A7 design developed by General Electric. The small diameter rotors were 3D printed and powered by brushless DC motors. The studies were implemented at a speed of up to 8500 rpm. Far-field acoustic measurements were performed in a noise-damped anechoic chamber. The noise characteristics of the brushless motors used in the experiments were investigated separately. For brushless motors, the main component is mechanical noise at the speeds of the motor shaft and its harmonics. For a uniaxial electric motor, the mechanical noise at the shaft speed increases with an increase in the rotational speed, while the noise at its higher harmonics decreases. The study of the coaxial electric motor showed an increase in mechanical noise at the higher harmonics of rotation. In experiments with insulated rotors, the tonal and broadband noise content was recorded. The study showed that with an increase in the rotational speed of a single rotor, the noise level rises from 65 to 80 dB. In this case, the maximum sound pressure shifts towards higher frequencies.

scholarly journals Spatiotemporal Evolution and Complexity of Urban Networks in China, 1978–2019: An Enterprise Linkages Perspective

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiayi Lu ◽  
Dongqi Sun
Keyword(s):  
Network Evolution ◽  
Small Scale ◽  
Spatiotemporal Evolution ◽  
Urban Network ◽  
Urban Networks ◽  
Scale Free ◽  
Core Networks ◽  
Wide Range ◽  
The Status ◽  
Peripheral Areas

With the development of globalization and informatization, the relationships among cities have become closer, and a “network” paradigm in urban studies is gaining attention. To examine China’s urban network evolution in a long time series, we used flow-based data to measure enterprise linkages from 1978 to 2019. We investigated the spatiotemporal evolution and complexity characteristics of urban networks in China and arrived at the following conclusions. (1) Intercity enterprise linkages in China have been continuously strengthened. The scale and density of urban networks have increased rapidly. Although the distribution of node cities’ importance and influence has been significantly unbalanced, the degree of which has lessened over time. (2) Network density has significantly improved since 1978, gradually forming a monocentric (Beijing) radial pattern. From the beginning of the twenty-first century, the status of core nodes (e.g., Shanghai) has gradually become prominent. Finally, four vertices stood out in 2019, forming a stable diamond structure. The spatial connection flows of enterprises constituted the core networks with Beijing as the center, skeleton networks with trunk lines formed by subnodes, and regional networks covering a wide range of peripheral areas. (3) China’s urban networks were typically small-scale and scale-free. However, the scale-free characteristics were weakened after 2010. The overall scale gap of intercity enterprise linkages gradually narrowed, and the structure of urban networks became optimized. Meanwhile, the urban networks were heterogeneous. There were more cities with headquarter-branches and active investment behaviors, which had strong influence and control over networks, playing their functions of “broker” and “transfer.”

Sign in / Sign up

Export Citation Format

Share Document