The wind speed resistance of a drone is generally 5 m/s, that is the drone is to be uncontrollable with more than 5 m/s. Therefore, our objective is to make the prototype of a wind resistant drone with vertical axis wind turbines. Two kinds of the vertical axis wind turbines were designed and the flow simulation was conducted in order to check the validity of the vertical axis wind turbines. Three kinds of the setting angle 0, 90 and 150 degrees of the vertical axis wind turbines were made by 3D printer. The blower experiment using the large fan was conducted and it was found that the setting angle 0 degree of the vertical axis wind turbines is the most effective and the distance of flow away by the wind was reduced by 26%.

High-speed collision of the droplet on a rigid wall produces a lateral jet emitted from the contact edge of the droplet in the direction perpendicular to the collision direction. In this study, we consider the droplet impact on a planar rigid surface with a sidewall. The numerical simulation is carried out for a spherical droplet with impact velocity 120 m/s using the multi-component Euler simulations. It was found that the impact pressure formed by the collision of the lateral jet on the sidewall is the same in the order of magnitude as that formed by the primary droplet collision.

The flow characteristics of the single-phase flow including the Newtonian and Non-Newtonian liquids were experimentally investigated in a horizontal rectangular micro-channel with a sudden expansion specifically the pressure changes across the expansion. The rectangular cross-sectional dimension has W_u × H_u (width × height) =0.50×0.50mm² on the upstream side and W_d × H_d(width × height) = 1.0 × 0.50mm² on the downstream side. Distilled water and three series of non-Newtonian shear-thinning liquid were used as the test liquid. The two different methods were used to determine the pressure change across the expansion. The expansion loss coefficient, K_e, was obtained from the pressure change data. The K_e for Newtonian liquid (water) is almost constant over a generalized Reynolds number tested. On the other side, the K_e for viscoelastic non-Newtonian liquids show unusual characteristics that are different from Newtonian fluids specially under low Reynolds number.

In this work, the effects of flow direction on flow patterns, gas slug velocity and gas slug length in a horizontal circular microchannel with an inner diameter of about 250 μm have been investigated by using a high speed camera. As the working fluids, nitrogen gas for the gas and aqueous solutions of concentration of glycerol of 33.5wt% and distilled water for the liquid were used. For the aqueous solutions the kinematic viscosities were 2.5 times and surface tensions were same as the ratios of their physical properties to those of distilled water. The superficial gas velocities, jG, were ranged from 0.01 to 13.0 m/s, and the superficial liquid velocities, j_L, were from 0.05 to 0.30 m/s.

As the camera shooting position moved downstream, the dominant region of the ring liquid film flow decreased, and the slag length tended to be longer than that of the gas slag upstream.

As the COVID-19 spreads widely around the world, the way it infects people has been researched. Typically, indoor infection is caused by droplets which from cough or sneeze. Virus-carrying droplets are easily affected by the airflow in the room and spread around. Areas with higher airflow retention time are more likely to concentrate droplets. Therefore, it is necessary to study the residence time of airflow in the room. In this article, a specific environment is modeled in 3D. Boundary conditions are set through data collection. Finally, the influence of boundary conditions on the residence time distribution and the average residence time is discussed through the simulation results.

Dielectric elastomer generator (DEG) can be used to harvest electric energy by changing the capacitance of dielectric elastomer (DE) under tensile force. In this work, we investigated the effect of the lateral pre-stretch ratio of DE and the input voltage on the power generation characteristics of the DEG under pure-shear loading. The advantage of increasing transverse pre-stretch ratio is mainly due to the increase of capacitance density of elastomer film at the maximum stretching, while increasing transverse pre-stretch is easy to cause loss-of-tension of DE, resulting in the decrease of energy density. The energy density increases first, and then decreases as transverse pre-stretch increases. With the increase of the charging voltage, the charging charge of DEG increases, but the voltage change decreases, so the energy density has a trend of increasing first and then decreasing. The peak value of energy density is 56 mJ/g and 62 mJ/g when the transverse pre-stretch is 3, and the charging voltage is 2 kV, respectively.

High-temperature water electrolysis cells and fuel cells will take an important role to establish carbon neutral society. Creep testing was performed in argon and hydrogen gases under absolute pressure of 0.12 MPa at 873 K in order to ensure the safety of those evolving hydrogen technologies that operate at elevated temperature. The materials were JIS SUY-1 soft electromagnetic iron and JIS SUS310S austenitic stainless steel. Results revealed that steady-state creep strain rate of both materials in hydrogen was accelerated than that in argon. Consequently, the creep life of both materials in hydrogen was shorter than that in argon. It was suggested that the role of hydrogen for the reduced creep life of both materials in hydrogen is to accelerate the creep deformation without changing the creep deformation mechanism.