Research On The Flow Field And Its PIV Measurement System Of The Liquid-continuous Impinging Streams Reactor

The organic matter in the power planet's water cycle will enable the growth of micro-organisms to form organic attachments such as algae. And the large increase of them will produce biogenic sediments on the heat transfer surface, which calls for water treatment; if not, will cause serious scaling problems affecting the economic security of the power plant. To remove the attchments,Chlorination was generally used in early sterilization of water cycle,which worked out badly in the water that contains ammonia and produced chloramine pollutants,so with the growing shortage of water resources and the increasingly stringent environmental requirements,it has been gradually replaced by the new technologies- biocides. There are two types of biocides -oxidized and non-oxidized. The former is mainly chlorine, bleaching powder, chlorine dioxide, ozone, etc. The latter is chlorinated phenols,quaternary ammonium salts and category such as acrolein. More or less either chioce has its own shortcomings. Such as chlorine dioxide, although by using it the bactericidal effect will not be affected by the impact of PH value, as well as the function of sterilization and spores and viruses killing, yet the disadvantages are also obvious,like troublesome dosing operation, slow degradation, insidiously drugs acting, instability with high consistency, inconvenient transportation with low consistency, difficult storage and short validity. Chlorinated phenols,another example, has the advantages of dosing convenience and better effect, but it will irritate eyes, skin and nasalmucous membrane and will cause environmental pollution after being discharged into the waters.Quatemary ammonium salts is quick,better and convenient with good durability and spin-off,however,a heavy dose of it can make the liquid medicine foam easily,therefore it requires salinity in circulating water should not be too high.The subject is to study a new physical method. In order to remove algae, the liquid-continuous impinging streams reactor used in lab is designed with the view to make use of a strong impact and shear stress from two fluid movement against each other. Therefore, we need make a further and meticulous study flowing field in the liquid- continuous impinging streams reactor. In this article,the researcher first establishes a mathematical model of liquid-continuous impinging streams, by studying the flowing field. And then, geometric model and physical model of liquid-continuous impinging streams reactor was built by using Fluent's software and the pre-processing software Gambit,based on which the reasercher conducts the numerical simulation on the internal flowing field to determine the optimal operating conditions and provide useful information for the optimized structure. Finally,the researcher designs and establishes a PIV measurement system device of a liquid- continuous impinging streams,and therefore realize the instantaneous flow measurement without contact.Flow field measurement is the basis of the design and scale-up of the industrial device. In order to provide useful data for the industrial application of the liquid-continuous impinging streams reactor, a PIV measurement system with two laser flashers of a liquid- continuous impinging streams which is quite different from the traditional one is established. In the new PIV measurement system,two laser flashers, red and green, are used.After the digital camera is triggered, the two flashers flash in a short interval during the exposure period. The red light and the green light illuminate the same region so that the image records the movements of tracing particles in two colors. Using digital image process technology, two images, the red one and the green one, can be obtained from the original image. Based on the two images, the flow field parameters can be calculated,as long as the power source is large enough. And therefore realize the instantaneous flow measurement without contact, and provide a convenient method for flow field measurement. PIV measurement system with two laser flashers includes the following:①hardware structure design in PIV measurement system. In order to acquire sequence images in PIV measurement system of a liquid- continuous impinging streams, two laser flashers, red and green, are used in PIV measurement system. After the digital camera is triggered, the two flashers flash in a short interval during the exposure period. The red light and the green light illuminate the same region so that the image records the movements of tracing particles in two colors. Using digital image process technology, two images, the red one and the green one, can be obtained from the original image. Based on the two images, the flow field parameters can be calculated. The method possesses predominant advantages:high speed field can be measured using an ordinary camera and the two images have determinate time labels, so the moving direction of the particles can be determined easily.Meanwhile, we can greatly reduce the cost. ②Software development in PIV measurement system. The control programs of the computer and the single chip achieve communication and human-computer interaction③Optical laser knife design in PIV measurement system. According to the demand of PIV measurement system, a special structure of collimating lens is put forward and the parameters of the lens is given. At the same time the pulse modulating driving circuit for LD is implemented. The lens has the characters of simple in structure, small in size, and the utilization ratio of light output of LD is over 90%. The driving circuit works well, and the pulse period and width can be adjusted precisely. The optical and circuit design also can be used for other applications, such as laser scanning, laser distance measurement, and etc.④Coordinating conversion method in PIV measurement system. In order to acquire flowing field parameters in PIV measurement system of a liquid- continuous impinging streams, a special coordinates mapping method from image space to real space is put forward. Based on neural net work, the method includes bellow steps. Firstly we put a board with grid pattern on it into a transparent cylinder container and fill the container with water. Secondly we adjust the board to ensure the axis of the container right goes through the grid plane. Thirdly a camera facing to the board is fixed outside the container. By taking picture of the gird and processing the picture with software tool, the training vector set is obtained, and after training the neural net work can mapping coordinates from image space to real word space correctly.⑤Flow field image processing and speed measurement method in PIV measurement system. In the article,the researcher mainly elaborates on image separation,particle image restoration,image enhancement,image denoising, partition, pattern matching, frame extraction,etc. Moreover, discussed the conversion from Bayer to RGB,flowing field image processing and speed calculation.