Axial thrust and power consumption of propellers in viscoelastic fluids exhibiting hysteresis effect

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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Hysteresis effect of propeller jet flows in viscoelastic fluids: Transformation process and turbulence intensity

Chemical Engineering Science ◽

10.1016/j.ces.2021.116506 ◽

2021 ◽

Vol 235 ◽

pp. 116506

Author(s):

Can Cao ◽

Matthias Kraume

Keyword(s):

Turbulence Intensity ◽

Viscoelastic Fluids ◽

Transformation Process ◽

Hysteresis Effect ◽

Jet Flows

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Compositional Tuning of Negative Differential Resistance in Bulk Silver Iodide Memristor

New Journal of Chemistry ◽

10.1039/d0nj05427e ◽

2020 ◽

Author(s):

SMITA GAJANAN NAIK ◽

Mohammad Hussain Kasim Rabinal

Keyword(s):

Power Consumption ◽

Negative Differential Resistance ◽

Silver Iodide ◽

Differential Resistance ◽

Fast Response ◽

Low Power Consumption ◽

Switching Effect ◽

Memory Switching ◽

Bulk Silver ◽

Emerging Memory

Electrical memory switching effect has received a great interest to develop emerging memory technology such as memristors. The high density, fast response, multi-bit storage and low power consumption are their...

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Flow behavior of viscoelastic fluids

AccessScience ◽

10.1036/1097-8542.yb110147 ◽

2015 ◽

Keyword(s):

Flow Behavior ◽

Viscoelastic Fluids

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Optimal design of a high homogeneous and small-size shim coil for atomic spin gyroscope based on 0-1 linear programming

International Journal of Applied Electromagnetics and Mechanics ◽

10.3233/jae-209319 ◽

2020 ◽

Vol 64 (1-4) ◽

pp. 165-172

Author(s):

Dongge Deng ◽

Mingzhi Zhu ◽

Qiang Shu ◽

Baoxu Wang ◽

Fei Yang

Keyword(s):

Linear Programming ◽

Power Consumption ◽

Low Power ◽

Optimization Design ◽

Structural Parameters ◽

Axial Position ◽

Low Power Consumption ◽

Optimal Method ◽

Atomic Spin ◽

Shim Coil

It is necessary to develop a high homogeneous, low power consumption, high frequency and small-size shim coil for high precision and low-cost atomic spin gyroscope (ASG). To provide the shim coil, a multi-objective optimization design method is proposed. All structural parameters including the wire diameter are optimized. In addition to the homogeneity, the size of optimized coil, especially the axial position and winding number, is restricted to develop the small-size shim coil with low power consumption. The 0-1 linear programming is adopted in the optimal model to conveniently describe winding distributions. The branch and bound algorithm is used to solve this model. Theoretical optimization results show that the homogeneity of the optimized shim coil is several orders of magnitudes better than the same-size solenoid. A simulation experiment is also conducted. Experimental results show that optimization results are verified, and power consumption of the optimized coil is about half of the solenoid when providing the same uniform magnetic field. This indicates that the proposed optimal method is feasible to develop shim coil for ASG.

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Analysis of Characteristics of Halogen and LED Automobile Lamps

Light & Engineering ◽

10.33383/2019-067 ◽

2020 ◽

pp. 57-62

Author(s):

Olga Yu. Kovalenko ◽

Yulia A. Zhuravlyova

Keyword(s):

Power Consumption ◽

Flip Chip ◽

Weather Conditions ◽

Luminous Flux ◽

Luminous Efficacy ◽

Colour Temperature ◽

Study Results ◽

Calculation Results ◽

Mandatory Rules ◽

Halogen Lamps

This work contains analysis of characteristics of automobile lamps by Philips, KOITO, ETI flip chip LEDs, Osram, General Electric (GE), Gtinthebox, OSLAMPledbulbs with H1, H4, H7, H11 caps: luminous flux, luminous efficacy, correlated colour temperature. Characteristics of the studied samples are analysed before the operation of the lamps. The analysis of the calculation results allows us to make a conclusion that the values of correlated colour temperature of halogen lamps are close to the parameters declared by manufacturers. The analysis of the study results has shown that, based on actual values of correlated colour temperature, it is not advisable to use LED lamps in unfavourable weather conditions (such as rain, fog, snow). The results of the study demonstrate that there is a slight dispersion of actual values of luminous flux of halogen lamps by different manufacturers. Maximum variation between values of luminous flux of different lamps does not exceed 14 %. The analysis of the measurement results has shown that actual values of luminous flux of all halogen lamps comply with the mandatory rules specified in the UN/ECE Regulation No. 37 and luminous flux of LED lamps exceeds maximum allowable value by more than 8 %. Luminous efficacy of LED lamps is higher than that of halogen lamps: more than 82 lm/W and lower power consumption. The results of the measurements have shown that power consumption of a LED automobile lamp is lower than that of similar halogen lamps by 3 times and their luminous efficacy is higher by 5 times.

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