It's a new technology for the concentration and reduction of desulfurization wastewater by the indirect air cooling tower,and relevant research on its evaporation mechanism has been rarely published.In this paper,indoor experiments are conducted to explore the evaporation characteristics of the evaporation tower and the evaporation law of desulfurization wastewater in the filler and analyze the factors affecting the evaporation characteristics,and a power plant adopting this technology is tested to verify the conclusion of the indoor experiments.The results show that the evaporation rate of the evaporation tower is positively correlated with the cross-sectional wind speed,water spray density,packing height and other parameters,and the influence of the interrupted wind speed on the evaporation rate is the most significant.During the operation of the evaporation tower,the temperature of desulfurization wastewater in the evaporation tank fluctuates by less than 0.5℃,and it is close to the wet bulb temperature of the outlet air of the evaporation tower where the air is closely saturated.The difference in vapor pressure has a positive linear relationship with that of mass fraction of the air in inlet and outlet,and the results of the model test conform to those of the actual one basically.On the condition of a ventilation rate of 817.56 m3/s,the evaporation efficiency of a mechanical ventilation cooling tower with a drenching area of about 400 m2 can reach 16.2-18.4 t/h,which basically meets the engineering needs of desulfurization wastewater concentration and reduction in millions of thermal power plants.
The heave plate plays a significant role in reducing the dynamic responses of floating wind turbines (FWTs) because the flow separation and vortex shedding around the sharp edges of heave plate provide viscous damping. This paper investigates the effect of different types of heave plates on the dynamic responses of a semi-submersible FWT. The single circular perforated heave plates and the double circular solid heave plates are compared to the original (single circular solid) heave plate of the OC4-DeepCwind semi-submersible FWT with the total structural properties of platform kept constant. OpenFAST is employed to conduct the time-domain simulations under five different combinations of wind and wave conditions. The heave and pitch natural period estimated from free decay tests decrease when the perforated heave plate is deployed. The double solid heave plate only increases the heave natural period. Compared to the single solid heave plate, the heave and pitch motions increase by up to 40% for the platforms with the perforated or double heave plates, except for the decreasing heave motion for the perforated heave plate under turbulent wind condition and a smaller pitch motion (up to 15%) under the turbulent wind or irregular wave and turbulent wind condition. The perforated heave plates result in the increasing tower base bending moment while the double heave plates have little influence on the tower base bending moment, only decrease by 8% under irregular wave and constant wind condition. The tensions of mooring line on the starboard side increase by up to 15% for the platforms with the perforated heave plates while the tensions for the double heave plates are quite close to those for the single solid heave plate. The surge motions and the upwind mooring line tensions are independent on the heave plate. Additionally, the mean pitch motions decrease by up to 7% for the double heave plates relative to the results for the single solid heave plate while the changes in the mean values of other dynamic responses is negligible.
The experimental investigation on the Mode-2 internal solitary waves(ISW)and its induced flow field in the continuous density pycnocline are carried out in a large stratified flume.The experimental simulation of the Mode-2 ISW in the continuous pycnocline is realized by using the principle of stratified fluid gravity collapse.The conductivity probe array and particle image velocimetry(PIV)are used to measure the Mode-2 ISW and its wave induced flow field.The geometrical characteristics of Mode-2 ISW waveform in the continuous pycnocline is obtained,and the non-uniform structures of the wave-flow are obtained,and the influence of wave amplitude variation on the characteristics of wave propagation factor and wave-flow field of Mode-2 ISW are obtained.The research shows that the geometric waveform of the Mode-2 ISW in the continuous pycnocline is presented as the convex and concave oval wave packets,and the non-uniform vertical structure of waveform is characterized by the non-uniform changes of the amplitude and wavelength with water depth.The convex and concave regions of the Mode-2 ISW packet form counterclockwise and clockwise circulations respectively,and the combination of the two forms a pair of upper and lower antisymmetric circulations to propagate forward together.The wave velocity of the Mode-2 ISW increases with the increase of wave amplitude,and the wavelength decreases with the increase of wave amplitude.The magnitudes of the horizontal and vertical flow velocity are positively correlated with the characteristic wave amplitude,and the former magnitude is greater than the latter one.The research results can improve the understanding of the Mode-2 ISW and its wave-induced flow field under the actual ocean stratification conditions.
In order to study the internal flow pattern transformation and the change law of bubble diameter in the gas-liquid two-phase flow disc pump,the visualization research and numerical simulation are used for analysis in this paper.The results show that when the inlet gas volume fraction increases from 1.12％to 27.67％,the flow pattern in the suction chamber changes from bubble flow to agglomerated bubble flow,slug flow and segregated flow.The bubble diameter at low gas content is small,and the gas-liquid mixing in the suction chamber is uniform and the flow is smooth.With the increase of gas content,the bubble diameter increases gradually,and the separation degree of gas-liquid two-phase in the suction chamber increases.Due to the particularity of the impeller structure of the disc pump,the blades in the leaf area of the front and rear cover plates play a barrier role.The gas phase gathers most violently at the edge of the blade in the leaf area,while the flow channel in the middle leafless area is wider and has higher permeability.Under the condition of 1 500 r/min and inlet gas volume fraction 7.11％,the local void fraction extreme value of the front edge of the blade in the blade area of the front cover plate increases to 3 times of the initial void fraction,the local void fraction extreme value of the blade edge in the blade area of the rear cover plate increases to 2 times of the initial void fraction,and the void fraction extreme value of the middle section of the bladeless area decreases to 2/3 of the initial void fraction.This study can provide a reference for analyzing the gas phase distribution and migration law in the disc pump impeller.
In the process of coastal bridge construction, cofferdams become necessary facilities to ensure the construction environment is dry and safe. However, during the construction period of coastal bridges, extreme surges and waves caused by typhoons can impose huge hydrodynamic loads on the cofferdam and a potential threat to the safety and integrity of the cofferdam. Therefore, it becomes valuable to assess the hydrodynamic loads of bridge cofferdam under extreme waves. Meanwhile, in the harsh marine environment, waves tend to propagate in multiple directions. However, previous studies mainly focused on the hydrodynamic characteristics of cofferdam by waves that propagate in one direction. Few studies were carried out on the hydrodynamic characteristics of cofferdam under the action of extreme waves in multiple directions. To fill in the gaps in previous research, this study numerically studied the complex wave hydrodynamics of cofferdam under multidirectional extreme waves. Effects of several major factors, i.e., significant wave height, peak wave period, water depth, spreading angle, incident wave angle, and submergence depth were systematically analyzed. It is desired that present research could enhance our understanding of the complex wave hydrodynamics of bridge cofferdam under multidirectional focused waves.
