Design and Optimization of Centralized Pneumatic Fertilizer Transporting System for Deep Fertilization Device in Paddy Field

Xiantao Zha,Guozhong Zhang,Yuhang Han,Jianwei Fu,Yong Zhou 한국유체기계학회 2021 International journal of fluid machinery and syste Vol.14 No.3

To improve the airflow distribution consistency of each branch in the pneumatic fertilizer transportation system, so as to reduce the influence of airflow instability on the uniformity and stability of fertilizer transportation, as well as the energy waste in the process of pneumatic fertilizer transportation, a centralized pneumatic fertilizer transportation system for deep fertilization device was designed. Through theoretical calculation, the needed air flow rate, airflow speed and fertilizer pipe diameter of the system were obtained, and the fan was selected. Based on the Fluent simulation and bench tests, the influence of three air distribution method of placing fan at the end of main duct, placing fan in the middle of main duct and centralized air distribution on the airflow velocity and consistency of each branch was analyzed. The results showed that the airflow consistency of each branch in the centralized air distribution method was the best. Taking the air velocity at the outlet of each branch and its variation coefficient as the evaluation index, single factor and orthogonal simulation tests was carried out to optimize the structural parameters of centralized air distribution device. The simulation results showed that the primary and secondary factors affecting the air distribution consistency were: A (sidewall inclination angle), B (branch diameter), C (branch distance), A×B (interaction between A and B), B×C (interaction between B and C), A×C (interaction between A and C), and all the factors and their interactions had significant effects. The best parameter combination was sidewall inclination angle 15°, branch diameter 32 ㎜, branch distance 43 ㎜. With the combination, the variation coefficient of airflow velocity was 0.27% in simulation test and 1.23% in bench test. This research optimized the structure and parameters of pneumatic fertilizer transporting system, and provided references for the design and optimization of pneumatic fertilization and seeding device.

A second order analytical solution of focused wave group interacting with a vertical wall

Yonggang Sun,Xiantao Zhang 대한조선학회 2017 International Journal of Naval Architecture and Oc Vol.9 No.2

The interaction of focused wave groups with a vertical wall is investigated based on the second order potential theory. The NewWave theory, which represents the most probable surface elevation under a large crest, is adopted. The analytical solutions of the surface elevation, velocity potential and wave force exerted on the vertical wall are derived, up to the second order. Then, a parametric study is made on the interaction between nonlinear focused wave groups and a vertical wall by considering the effects of angles of incidence, wave steepness, focal positions, water depth, frequency bandwidth and the peak lifting factor. Results show that the wave force on the vertical wall for obliquely-incident wave groups is larger than that for normally-incident waves. The normalized peak crest of wave forces reduces with the increase of wave steepness. With the increase of the distance of focal positions from the vertical wall, the peak crest of surface elevation, although fluctuates, decreases gradually. Both the normalized peak crest and adjacent crest and trough of wave forces become larger for shallower water depth. For focused wave groups reflected by a vertical wall, the frequency bandwidth has little effects on the peak crest of wave elevation or forces, but the adjacent crest and trough become smaller for larger frequency bandwidth. There is no significant change of the peak crest and adjacent trough of surface elevation and wave forces for variation of the peak lifting factor. However, the adjacent crest increases with the increase of the peak lifting factor.

A second order analytical solution of focused wave group interacting with a vertical wall

Sun, Yonggang,Zhang, Xiantao The Society of Naval Architects of Korea 2017 International Journal of Naval Architecture and Oc Vol.9 No.2

The interaction of focused wave groups with a vertical wall is investigated based on the second order potential theory. The NewWave theory, which represents the most probable surface elevation under a large crest, is adopted. The analytical solutions of the surface elevation, velocity potential and wave force exerted on the vertical wall are derived, up to the second order. Then, a parametric study is made on the interaction between nonlinear focused wave groups and a vertical wall by considering the effects of angles of incidence, wave steepness, focal positions, water depth, frequency bandwidth and the peak lifting factor. Results show that the wave force on the vertical wall for obliquely-incident wave groups is larger than that for normally-incident waves. The normalized peak crest of wave forces reduces with the increase of wave steepness. With the increase of the distance of focal positions from the vertical wall, the peak crest of surface elevation, although fluctuates, decreases gradually. Both the normalized peak crest and adjacent crest and trough of wave forces become larger for shallower water depth. For focused wave groups reflected by a vertical wall, the frequency bandwidth has little effects on the peak crest of wave elevation or forces, but the adjacent crest and trough become smaller for larger frequency bandwidth. There is no significant change of the peak crest and adjacent trough of surface elevation and wave forces for variation of the peak lifting factor. However, the adjacent crest increases with the increase of the peak lifting factor.

Preparation and evaluation of surfactant-stabilized graphene sheets and piezoresistivity of GPs/cement composite

Zhu Siyue,Qin Xiantao,Zou Zuxu,Zhang Rongtang,Jiang Yi 한국탄소학회 2020 Carbon Letters Vol.30 No.1

For applications in cement-based materials, studies on carbon-based nanomaterials have been almost exclusively on carbon nanotubes, carbon nanofbers, and graphite oxide. Graphene sheets (GPs), as a kind of carbon-based nanomaterials, show unusual mechanical, electrical, optical, and other properties. In this paper, the main focus is to enhance the efect of GPs by improving dispersion through ultrasonication and use of surfactant. Then, dispersion and stability are quantitatively measured by comparing absorbance spectra through spectrophotometry and qualitatively observed through digital imaging and SEM imaging. Therefore, the dispersing protocol is optimized and the most efective and stable dispersion is achieved. At last, the piezoresistivities under compressive load of GPs/cement composites pastes at diferent additions of GPs are studied by comparing with plain cement paste.

A study of hydroelastic behavior of hinged VLFS

Sun, Yonggang,Lu, Da,Xu, Jin,Zhang, Xiantao The Society of Naval Architects of Korea 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged two-module structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.

A study of hydroelastic behavior of hinged VLFS

Yonggang Sun,Da Lu,Jin Xu,Xiantao Zhang 대한조선학회 2018 International Journal of Naval Architecture and Oc Vol.10 No.2

This paper introduces a new method to study the hydroelastic behavior of hinged Very Large Floating Structures (VLFSs). A hinged twomodule structure is used to confirm the present approach. For each module, the hydroelasticity theory proposed by Lu et al. (2016) is adopted to consider the coupled effects of wave dynamics and structural deformation. The continuous condition at the connection position between two adjacent modules is also satisfied. Then the hydroelastic motion equation can be established and numerically solved to obtain the vertical displacement, force and bending moment of the hinged structure. The results calculated by the present new method are compared with those obtained using three-dimensional hydroelasticity theory (Fu et al., 2007), which shows rather good agreement.