scholarly journals Effect of Ducted Multi-Propeller Configuration on Aerodynamic Performance in Quadrotor Drone

Drones ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 101
Author(s):  
Yi Li ◽  
Koichi Yonezawa ◽  
Hao Liu
Keyword(s):  
Optimal Design ◽  
High Performance ◽  
Lift Force ◽  
Force Production ◽  
Aerodynamic Performance ◽  
Aerodynamic Design ◽  
Cfd Simulations ◽  
Height Difference ◽  
Noticeable Effect ◽  
Propeller Design

Motivated by a bioinspired optimal aerodynamic design of a multi-propeller configuration, here we propose a ducted multi-propeller design to explore the improvement of lift force production and FM efficiency in quadrotor drones through optimizing the ducted multi-propeller configuration. We first conducted a CFD-based study to explore a high-performance duct morphology in a ducted single-propeller model in terms of aerodynamic performance and duct volume. The effect of a ducted multi-propeller configuration on aerodynamic performance is then investigated in terms of the tip distance and the height difference of propellers under a hovering state. Our results indicate that the tip distance-induced interactions have a noticeable effect in impairing the lift force production and FM efficiency but are limited to small tip distances, whereas the height difference-induced interactions have an impact on enhancing the aerodynamic performance over a certain range. An optimal ducted multi-propeller configuration with a minimal tip distance and an appropriate height difference was further examined through a combination of CFD simulations and a surrogate model in a broad-parameter space, which enables a significant improvement in both lift force production and FM efficiency for the multirotor, and thus provides a potential optimal design for ducted multirotor UAVs.

Innovative Variable Turbine Concept for Turbochargers

2011 ◽  
Author(s):  
Elias Chebli ◽  
Michael Casey ◽  
Markus Mu¨ller ◽  
Siegfried Sumser ◽  
Gernot Hertweck ◽  
...  
Keyword(s):  
Aerodynamic Performance ◽  
Cfd Simulations ◽  
Flow Variability ◽  
Variable Turbine Geometry ◽  
Turbine Efficiency ◽  
New Concepts ◽  
Specific Speed ◽  
Turbine Impeller ◽  
Flow Cross ◽  
Wide Operating

New concepts for the optimisation of supercharging systems have been analysed to improve fuel consumption, emissions and transient diesel engine response. In addition to the conventional VTG (Variable Turbine Geometry) where the variability takes place upstream of the turbine impeller, a new innovative variable turbine geometry called VOT (Variable Outlet Turbine) is investigated in this paper where the variability takes place at impeller exit. The flow variability is achieved by variation of the flow cross-section at the turbine outlet using an axial displacement of a sliding sleeve over the exducer and provides a simple solution for flow variability. The flow field of the VOT is calculated by means of steady state 3D-CFD simulations to predict the aerodynamic performance as well as to analyse the loss mechanisms. The VOT design is optimised by finding a good balance between clearance and outlet losses to improve the turbine efficiency. Furthermore, experimental results of the VOT are presented and compared to a turbine equipped with a waste gate (WG) that verify the efficiency advantage of the VOT. In general, it is found that the use of the VOT at high specific speed is important to reduce the outlet losses and to improve the turbine efficiency over a wide operating range.

Optimal design for a high performance H-JLTFET using HfO2 as a gate dielectric for ultra low power applications

RSC Advances ◽  
2014 ◽  
Vol 4 (43) ◽  
pp. 22803-22807 ◽  
Author(s):  
Pranav Kumar Asthana ◽  
Bahniman Ghosh ◽  
Shiromani Bal Mukund Rahi ◽  
Yogesh Goswami
Keyword(s):  
Optimal Design ◽  
Low Power ◽  
Field Effect ◽  
High Performance ◽  
Field Effect Transistor ◽  
Gate Dielectric ◽  
Ultra Low Power ◽  
Effect Transistor ◽  
Tunnel Field Effect Transistor

In this paper we have proposed an optimal design for a hetero-junctionless tunnel field effect transistor using HfO2 as a gate dielectric.

Optimal design for high-performance passive dynamic vibration absorbers under random vibration

2019 ◽  
Vol 195 ◽  
pp. 469-489 ◽  
Author(s):  
Eduardo Barredo ◽  
J.G. Mendoza Larios ◽  
Jan Mayén ◽  
A.A. Flores-Hernández ◽  
Jorge Colín ◽  
...  
Keyword(s):  
Optimal Design ◽  
High Performance ◽  
Random Vibration ◽  
Vibration Absorbers ◽  
Dynamic Vibration ◽  
Dynamic Vibration Absorbers

scholarly journals Three-dimensional optimal design of a cooled turbine considering the coolant-requirement change

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 768-778
Author(s):  
Wei Ba ◽  
Ziyuan Wang ◽  
Xuesong Li ◽  
Chunwei Gu
Keyword(s):  
Optimal Design ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Aerodynamic Performance ◽  
Pressure Surface ◽  
Component Efficiency ◽  
Requirement Change ◽  
Cooling Air ◽  
Gas Turbine Cycle

Abstract Cooling technology is widely applied in modern turbines to protect the turbine blades, and extracting high-pressure cooling air from a compressor exerts a remarkable influence on the gas-turbine performance. However, the three-dimensional optimal design of a turbine in modern industrial practice is usually carried out by pursuing high component efficiency without considering possible changes in coolant requirement; hence, it may not exactly lead to improvement in the gas-turbine cycle efficiency. In this study, the turbine stator was twisted and leaned to achieve higher comprehensive efficiency, which is the cycle-based efficiency definition for a cooled turbine that considers both turbine aerodynamic performance and coolant requirement. First, the influence of twist and compound lean on turbine aerodynamic performance, considering stator-hub leakage, was investigated. Then, a method to predict the coolant requirement for turbines with different stator designs was applied, to evaluate coolant-requirement change at the design condition. The optimized turbines were finally compared to demonstrate the necessity of considering the coolant-requirement change in the optimal design. This indicated that proper twisting to open the throat area in the stator hub and compound lean to the pressure surface side could help improve the cooled-turbine comprehensive efficiency.

scholarly journals Investigation of High Lift Force Generation of Dragonfly Wing by a Novel Advanced Mode in Hover

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 59
Author(s):  
Xiaohui Su ◽  
Kaixuan Zhang ◽  
Juan Zheng ◽  
Yong Zhao ◽  
Ruiqi Han ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Expenditure ◽  
Lift Force ◽  
Lift Coefficient ◽  
Aerodynamic Performance ◽  
Dynamic Stall ◽  
Force Generation ◽  
High Lift ◽  
Dragonfly Wing ◽  
Symmetrical Mode

In the paper, a novel flapping mode is presented that can generate high lift force by a dragonfly wing in hover. The new mode, named partial advanced mode (PAM), starts pitching earlier than symmetric rotation during the downstroke cycle of the hovering motion. As a result, high lift force can be generated due to rapid pitching coupling with high flapping velocity in the stroke plane. Aerodynamic performance of the new mode is investigated thoroughly using numerical simulation. The results obtained show that the period-averaged lift coefficient, CL, increases up to 16% compared with that of the traditional symmetrical mode when an earlier pitching time is set to 8% of the flapping period. The reason for the high lift force generation mechanism is explained in detail using not only force investigation, but also by analyzing vortices produced around the wing. The proposed PAM is believed to lengthen the dynamic stall mechanism and enhance the LEV generated during the downstroke. The improvement of lift force could be considered as a result of a combination of the dynamic stall mechanism and rapid pitch mechanism. Finally, the energy expenditure of the new mode is also analyzed.

Enhanced Investigations of High-Performance SI-Engines by Means of 3D-CFD Simulations

2015 ◽  
Author(s):  
Marlene Wentsch ◽  
Antonella Perrone ◽  
Marco Chiodi ◽  
Michael Bargende ◽  
Donatus Wichelhaus
Keyword(s):  
High Performance ◽  
Cfd Simulations ◽  
Si Engines

Residual Stress in Silicon Caused by Cu-Sn Wafer-Level Packaging

2013 ◽  
Author(s):  
Maaike M. V. Taklo ◽  
Astrid-Sofie Vardøy ◽  
Ingrid De Wolf ◽  
Veerle Simons ◽  
H. J. van de Wiel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Integrated Circuit ◽  
High Performance ◽  
White Light Interferometry ◽  
Wafer Level ◽  
Noticeable Effect ◽  
Micro Raman Spectroscopy ◽  
Wafer Level Packaging ◽  
Mems Device ◽  
Specific Technology

The level of stress in silicon as a result of applying Cu-Sn SLID wafer level bonding to hermetically encapsulate a high-performance infrared bolometer device was studied. Transistors are present in the read out integrated circuit (ROIC) of the device and some are located below the bond frame. Test vehicles were assembled using Cu-Sn SLID bonding and micro-Raman spectroscopy was applied on cross sectioned samples to measure stress in the silicon near the bond frame. The test vehicles contained cavities and the bulging of the structures was studied using white light interferometry. The test vehicles were thermally stressed to study possible effects of the treatments on the level of stress in the silicon. Finite element modeling was performed to support the understanding of the various observations. The measurements indicated levels of stress in the silicon that can affect transistors in regions up to 15 μm below the bond frame. The observed levels of stress corresponded well with the performed modeling. However, no noticeable effect was found for the ROIC used in this work. The specific technology used for the fabrication of the ROIC of a MEMS device is thus decisive. The level of stress did not appear to change as a result of the imposed thermal stress. The level of stress caused by the bond frame can be expected to stay constant throughout the lifetime of a device.

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