Insight into the interaction mechanism between liquid action and cone structure in liquid-containing gas-solid spouted fluidized bed reactors

An electronic experimental set-up was developed to evaluate three seed-metering mechanisms, viz. slanting, semi- circular and rectangular shape for three paddy varieties and to investigate the influence of the selected levels of variables, viz. forward speed, cell shape and inclination of seed-metering plate on performance parameters of seed- metering. Mean seed spacing, miss index and seed damage were found to increase with increase in forward speed and angle of inclination while multiple index decreased with increase in forward speed and angle of inclination for all metering plates tested. Precision decreased with increase in forward speed and with increase in angle of inclination, it increased initially up to optimum value and then decreased. The mean seed spacing of 14.8 cm close to theoretical seed spacing of 15 cm, highest quality feed index of 88.1%, lowest miss index of 6.1% and minimum seed damage of 0.38% were observed in slanting type metering plate at an angle of 35º with the horizontal and at a forward speed (belt speed) of 2 km/h. Hence, for design of precision paddy planter, the optimum parameters, like slanting type metering plate with angle of inclination 35º and forward speed of 2 km/h can be used to achieve best results.

Vertical mattress configuration is the strongest of all other configurations and the repairing devices of meniscus repair. The purpose was whether increasing the inclination angle between two strands of the vertical mattress configuration by increasing the amount of meniscus tissue captured would enhance the initial strength of the construction. A 2-cm long anteroposterior vertical longitudinal incision was created in two groups of bovine medial menisci. In the first group, the distance between the two vertical suture strands and the vertical horizontal sutures on the capsular side of the meniscal lesion was 2 mm (Group 1). In the second group, the distance was 5 mm (Group 2). The following repair specimens underwent cyclic loading prior to loading the failure testing. The endpoints included ultimate failure load (N), stiffness (N/mm) and cyclic displacement (mm) after the 100 cycles and the mode of failure. Group 1 (2 mm) (90.7 (±19.9) N) had lower ultimate load than Group 2 (5 mm) (120.8 (±24.5)) (P < 0.05). Stiffness and displacements during the cycling were not different between the groups (n.s.). All specimens failed by suture rupture. Increased inclination angle with increased distance between the two vertical suture strands on the capsular side of the meniscal lesion resulted in higher failure load compared to control group with lower inclination angle and distance on the capsular side.

By employing ray-tracing techniques, we investigate the shadow images of rotating Bardeen black holes surrounded by perfect fluid dark matter. We consider two models for the background light source, namely the celestial light source and thin accretion disk model. For the celestial light source model, the main focus is on the impact of variations in the relevant parameters and observational inclination angle on the shape and size of the black hole shadow. The results indicate that an increase in the magnetic charge G leads to a reduction in the shadow’s deformation, whereas an increase in the dark matter parameter α produces the opposite effect. For the thin accretion disk model, the optical appearance of the black hole strongly depends on the radiative properties of the accretion disk, as well as the observational inclination angle and the spacetime parameters. As the observational inclination angle increases, the observed flux of both direct and lensed images shifts toward the lower region of the image. It is evident that an increase in G results in a reduction of both the shadow area and the photon ring, and an increase in α exhibits a similar influence. In addition, we examined the redshift effect of the image, the results show that the redshift dominates at low inclination angles, while the blueshift effect emerges significantly at higher inclination angles. These results for the rotating Bardeen black hole surrounded by perfect fluid dark matter could serve as observational signatures to distinguish it from other black hole models.

This paper presents a three-dimensional numerical model to study the performance of a photovoltaic (PV) module integrated with phase change material (PCM) at different inclinations and compare it with that of PV only system. Numerical simulation using the commercial finite-element software COMSOL Multiphysics is carried out to evaluate the system. Inclinations angles (θ) from 0° to 45° are considered for the study in steps of 15°. The results show that the inclination angle has a substantial impact on the performance of the PV-PCM system. Natural convection heat flow in the melted PCM contributes significantly to the system’s performance at higher inclination angles. The average PV temperature decreases with the increase in inclination angle. The maximum drop in temperature, 40.44 °C, when compared to PV alone system, is observed for 45° inclination. The maximum percentage increment in PV efficiency varies from 26.05% to 27.16% when θ increases from 0° to 45°. The time taken for the complete melting of PCM improves from 141.5 min for θ = 0° to 125 min for θ = 45°. The thermal energy stored in PCM is enhanced from 25.6 kJ at θ = 0° to 27.5 kJ at θ = 45°.

Electrochemical impedance simulation of porous electrodes with variously shaped pores using 3-dimensional finite element method

Nusselt number-friction characteristic for a twisted rib roughened rectangular duct using liquid crystal thermography

Experimental investigation has been performed to investigate the influence of inclination angle on the film cooling performance of two typical diffuser shaped hole configurations, including laidback hole and laidback fanshape hole, using transient liquid crystal measurement technique. Under very small blowing ratio, increase of inclination angle has very small influence on the film cooling effectiveness of laidback fanshape hole configuration. With the increase of blowing ratio, large inclination angle notably reduces its film cooling effectiveness, especially in the upstream region. For film cooling of laidback hole configuration, the increase of inclination angle reduces the film cooling effectiveness under small blowing ratio due to the lift-off of film jets, while produces better film coverage and higher film cooling effectiveness under larger blowing ratios in the downstream region due to the reattachment of lift-off film jets. The increase of inclination angle reduces the heat transfer coefficient for film cooling of laidback fanshape hole configuration in the upstream region. For film cooling of laidback hole configuration, heat transfer coefficient is higher in the upstream region for large inclination angle case due to the enhancement effect of strong counter-rotating vortex pair, while laidback hole with small inclination angle has relatively higher heat transfer coefficient in the downstream region. Under very large blowing ratio, the counter-rotating vortex pair produce two intensely enhanced heat transfer region of spindle shape for film cooling of holes with large inclination angle. From the aspect of heat flux ratio, increase of inclination angle is beneficial to the thermal protection of laidback hole film cooling under large blowing ratio. For both diffuser shaped hole configurations, holes with large inclination angle have larger discharge coefficient due to smaller aerodynamic loss in the hole.

Steam condensation with non-condensable gas exists widely in petro-chemical, power plant and seawater desalination processes. Super-hydrophobic surfaces with high contact angle could be an promising condensing surface to promote DWC and enhance heat transfer. As pure steam condensing droplet completely occupies micro/nano-structures of super-hydrophobic surfaces, super-hydrophobic function becomes “invalid”. For stream-air mixture vapor, the non- condensable gas would occupy the micro/nano-structures instead of water. Droplets form Cassie or transition wetting mode, holding or partly holding super-hydrophobic feature. Inclination angle of the tube can influence the shape, size and dynamic characteristics of the condensing droplets, thus changing the heat transfer performance. Therefore, for getting deeply insights of the effect of the non-condensable gas on condensation heat transfer, it is necessary to study the condensing drops characteristics on super-hydrophobic tube for different inclined angles. According to dropwise condensation model, increasing contact angle hysteresis, departure droplet size, sweeping period would reduce the condensation heat transfer efficiency. In this paper, dropwise condensation is performed on super-hydrophobic copper tube, departure droplet size, sweeping period and the phenomenon of contact angle hysteresis are thoroughly studied and are compared with the case of hydrophobic surface or pure steam to explore the influence of inclined angle and surface wettability on droplet dynamics to achieve condensation heat transfer enhancement. The experimental result shows: (1) On the top of copper tube, for the condensation of steam with 10% non-condensable gas, the contact angle hysteresis on super-hydrophobic surface is smaller than that on hydrophobic surface. Compared with pure steam condensation on super-hydrophobic surface, the contact angle hysteresis of mixed steam is smaller because the non- condensable gas fills the micro/nano-structures. However, on the middle and bottom parts of the tube, the contact angle hysteresis on super-hydrophobic surface is greater than that on hydrophobic surface for the condensation of both pure steam and mixed steam. This phenomenon indicates that the contact angle hysteresis is determined by surface wettability instead of inclination angle. (2) The departure droplet size on super-hydrophobic surface increases with the inclination angle and the opposite trend is found on hydrophobic surface. With the increase of inclination angle, the support force provided by the tube would increase and change direction. So the wettability of the surface and departure droplet size would be changed. (3) The sweeping period of droplet on super-hydrophobic surface is longer because the micro/nano-structures increase the adhesion between the surface and the droplets. With the increase of the inclination angle, the sweeping period decreased slightly, shorter than the sweeping time when the tube is vertical. The sweeping period of vapor with non-condensable gas condensation is greater than that of pure steam. The presence of non-condensable gas increases thermal resistance, thus slowing down the drop growth rate and increasing the sweeping period. To sum up, on the top of copper tube, the contact angle hysteresis on super-hydrophobic surface is smaller than that on the hydrophobic surface. However, the totally opposite trend is found on the middle and bottom parts of the tube. The departure droplet size on super-hydrophobic surface increases with the inclination angle. The sweeping period of droplet on super-hydrophobic surface is longer. This work offers a new avenue to further enhance heat transfer of condensation with non-condensable gas.

Coarse particle-laden flows in inclined pipes are commonly encountered in a wide range of industrial processes. A fully coupled CFD-DEM model considering various fluid-particle interphase forces and turbulence-particle interactions is used to simulate coarse particles transported in inclined pipes. The energy dissipation is calculated from both the macro and micro perspectives. The effects of pipe’s inclination angle, particle concentration, conveying speed and particle diameter on the hydraulic transport characteristics and the energy dissipations are analyzed. The results showed that, with the increase in inclination angle, the deposited particles were gradually dispersed. Pressure drop and energy dissipation displayed a peak at 60°. Both the parameters increased with the increases in particle concentration and conveying speed in 60° inclined pipe. The energy dissipation was mainly due to the turbulent dissipation, wall friction, mean velocity field and particles’ gravity. The results further showed that the modulations in the fluid due to particle distribution could significantly change the energy dissipation caused by the fluctuating velocity, thus resulting in the maximum pressure drop and energy dissipation at 60°. The particle-fluid energy dissipation increased almost linearly with the increase in conveying speed, while it varied nonlinearly with the increase in inclination angle and particle parameters.

Free convection heat transfer inside vertical and inclined elliptic tubes with different axis ratio and different inclination and orientation angles

Flame spread over discrete fuels is a typical phenomenon in fire scenes. Experimental and theoretical research on flame spread over discrete thermally thin fuels separated by air gaps with different inclination angles was conducted in the present study. Experiments with six inclination angles ranging from 0° to 85° and various fuel coverage rates from 0.421 to 1 were designed. The flame spread behavior, the characteristic flame size, and the flame spread rate were analyzed. The results show that the flow pattern, stability, and flame size exhibit different characteristics with different inclination angles and gap sizes. As the inclination angle increases, particularly with smaller gaps, turbulent and oscillating flames are observed, while larger gap sizes promote flame stability. The mechanism of flame propagation across the gap depends on the interplay between the flame jump effect and heat transfer, which evolves with gap size. Average flame height, average flame width, and flame spread rate initially increase and then decline with the increase in fuel coverage, peaking at fuel coverage rates between 0.93 and 0.571 for different inclination angles. A theoretical model is proposed to predict the flame spread rate and the variation in the flame spread rate with inclination angle and fuel coverage. Furthermore, the map determined by inclination angle and fuel coverage is partitioned into distinct regions, comprising the accelerated flame spread region, the flame spread weakening region, and the failed flame spread region. These findings provide valuable insights into flame spread dynamics over discrete thermally thin fuels under diverse conditions.

Droplet impinging on an inclined cylinder is different from that on a horizontal one in some ways. However, there is still a lack of in-depth study on its dynamic behavior. In this study, a numerical model of droplet impinging on a superhydrophobic inclined cylindrical surface was established by incorporating a dynamic contact angle model. Droplet motion patterns, sliding behavior, spreading and shrinking behavior, and contact time after droplet impinging were discussed under the influences of inclination angle and Weber number. Results show that under different conditions, droplets may exhibit four motion patterns: full rebound, pure slide, fragmentation, and oscillation. Pure slide is an inherent motion pattern for droplet impinging on an inclined surface, and full rebound is caused by the different sliding velocities of leading and trailing edges. Leading edge's sliding distance curve is convex and trailing edge's one is concave. The dimensionless sliding distance of the droplet rises with Weber number and inclination angle, and the effect of Weber number on it lessens at small inclination angles. The time for the droplet to reach maximal spreading length in axial direction gradually exceeds that in circumferential direction with the increase in inclination angle, and the non-monotonicity of the axial spreading length during the shrinking process disappears when an inclination angle is introduced. When the Weber number is less than 15.28 and the inclination angle rises from 0° to 80°, the contact time increases by 58.8%. This growth is even more pronounced when the Weber number is larger.

Micro end milling is a main method for the fabrication of microgroove parts which are widely applied in biology, electronics, precision machinery, and other fields. However, the machining quality of microgroove is difficult to meet requirements due to size effect, and the machined grooves easily produce high surface roughness and poor form accuracy during micro milling. In this paper, in order to investigate the effects of machining inclination angles on the performance of micro ball end milling, the micro milling experiments on Ti-6Al-4V are carried out by setting the micro ball end mill with different inclination angles in feed direction, cross-feed direction, and the combination of the two directions, respectively. The results show that the tool orientation strategy has significant influences on the quality of microgroove and can reduce the roughness and improve the form accuracy. With increase of the absolute value of inclination angle along feed direction from 0° to 45°, the surface roughness has a decreasing trend, and the chips adhesion and texture becomes inconspicuous. When inclination angle along feed direction is 30° and 45°, the combination inclination angle strategy has no obvious influences on the surface roughness with increase of inclination angle along cross-feed direction. However, the combination inclination angles strategy can reduce the maximum form deviation and improve the form accuracy of the groove. Based on the results, an optimal combination inclination angles with feed direction 45° and cross-feed direction 20° strategy is proposed to machining the microgroove.

Film cooling performances of laidback hole and laidback fan-shaped hole have been investigated using transient liquid crystal measurement technique. For film cooling of laidback hole, the increase of inclination angle reduces the film cooling effectiveness under small blowing ratio, while produces better film coverage and higher film cooling effectiveness under larger blowing ratios. Heat transfer coefficient is higher in the upstream region of laidback hole film cooling with large inclination angle, while laidback hole with small inclination angle has relatively higher heat transfer coefficient in the downstream region. The increase of inclination angle reduces the film cooling effectiveness and heat transfer coefficient of laidback fan-shaped hole film cooling, especially in the upstream region. Increase of inclination angle is beneficial to the thermal protection of laidback hole film cooling under large blowing ratio. Film hole with large inclination angle has larger discharge coefficient due to smaller aerodynamic loss in the hole.

In present study, a new type of three-dimensional pin–fin plate with elliptical cross-section was proposed. Steam condensation on the proposed plates with different geometric parameter was experimentally studied at atmospheric pressure. The effects of horizontal pin spacing, pin height and inclination angle on condensation heat transfer were investigated. The results showed that all the elliptical pin-fin plates exhibited substantially better performance than the flat plate. The highest enhancement ratio of 2.33 was achieved when the elliptical pin-fin plate was vertically placed. The geometric parameter and inclination angle showed a strong influence on the performance of elliptical pin-fin plate. The performance of elliptical pin-fin plate was enhanced when the pin height increased from 1.2 mm to 2.0 mm or the horizontal pin spacing increased from 1.2 mm to 2.0 mm. The strengthening effect of pin height became weaker with the increase of horizontal pin spacing. When the inclination angle increased from 0° to 60°, the heat flux and average condensation heat transfer coefficient decreased by 16 and 25%, respectively. With the increase of inclination angle, the gravity effect in the direction of condensate flow decreased, resulted in the deterioration of heat transfer. The results can provide reference for practical engineering applications and the further optimization design of pin-fin enhanced condensation structure.