【作者】 刘颖；

【导师】 田瑞峰；

【作者基本信息】 哈尔滨工程大学 ， 核科学与技术， 2016， 硕士

【摘要】 众所周知,旋风分离器作为蒸汽发生器中的初级分离器,具有体积小、结构简单、耐高压、分离效率高等特点。近些年来,人们针对旋风分离器的性能以及结构的优化做了大量的研究工作,但是,对于位于两级旋风分离装置上方的重力沉降空间的研究较少。同时,为了能够更好的满足蒸汽发生器对汽水分离性能的要求,许多人开始研究新的结构形式的分离器。本文根据一种新型的汽水分离器—两级旋风分离装置,建立了几何模型,并且进行了数值模拟研究。首先,针对蒸汽发生器中重力沉降空间,建立几何模型,并进行了数值计算,研究影响重力空间分离效率的因素。建立几何模型时,为了更加准确的模拟重力空间入口处的气流速度和方向,在其入口处设置有一级旋风分离器。计算结果表明:沉降空间的分离效率随着其高度的增大先逐渐增大后保持不变。其次,对两级旋风分离装置进行结构分析、建立模型、划分网格,并且完成两级旋风分离装置的数值模拟计算。为了与实验结果进行比较分析,在计算过程中采用常温常压下的空气-水作为流体工质。模拟计算中,利用RNG k-ε模型对两级旋风分离装置中的流场进行了数值模拟,得出了其流场中的压力分布特性以及速度分布特性。同时,利用RNGk-ε模型、DPM模型和EWF模型相结合的方法对两级旋风分离装置的分离特性进行了分析研究,并且研究分析了两级旋风分离装置壁面处液膜的运动情况。结果表明:1)两级旋风分离装置进出口压降与入口速度的平方呈线性关系;2)其分离效率随着入口速度的增大而增大;3)壁面液膜对两级旋风分离装置的进出口压降和分离效率有一定影响,但影响不大。最后,通过对高压情况下两级旋风分离装置中单相和两相流场的数值模拟,研究了不同结构参数对其进出口压降和分离效率的影响。通过总结结构参数的影响规律,对两级旋风分离装置进行了简单的初步结构优化。更多还原

【Abstract】 As is known to all, cyclone separator is the primary separator in the steam generator,with the advantages of small volume, simple structure, high pressure resistance, high separation efficiency, etc. People have studied a lot of research work on the performance and the structure optimization of cyclone separator in recent years,however the research on the gravity settling of the space,which is upon the cyclone separator, in the steam generator is rarely known by people. At the same time, many people begin to research new structure of the separator to meet the requirement of steam-water separator in the steam generator. This paper has established the geometric model of a new type of steam separator- the two stage cyclone separating device, and has carried out the numerical simulation research on it.Firstly, this paper has set up the geometric model of the gravity settling space of the steam generator, which is based on the construction of the gravity settling space, carried out the numerical calculation, and analyzed the factors that influence efficiency of gravity separation space. There are a certain number of primary cyclone separators at the entrance of the gravity settling space, whose purpose is more accurate to simulate the velocity and the direction of the velocity at the entrance of the gravity space. The results of the numerical simulation on the gravity space show that the separation efficiency of the gravity space increases gradually firstly and then remains the same with the increase of the height of the gravity space.Secondly, the numerical simulation has been carried out about the single-phase and the two-phase flow fields in the two stage cyclone separating device after establishing the model and meshing. In order to compare with the experimental results, air and water under the atmospheric pressure was used to be the fluid medium in the separator during the process of calculation. The model of RNG k-ε was used in the simulation of the single-phase. And the pressure field and the velocity field in the two stage cyclone separating device was analyzed. In addition, the study on the separation characteristics of the two stage cyclone separating device by combining the method of the RNG k-ε model, the DPM model and the EWF model. At the same time, the motion of the liquid film on the wall of the two stage cyclone separating device was analyzed. The results of the numerical simulation show that: 1)The pressure drop of the two stage cyclone separating device has a linear relation with the square of the inlet velocity; 2) The separation efficiency increases with the increase of inlet velocity; 3) The motion of the wall film does not effect the pressure drop and separation efficiency of the two stage cyclone separating device obviously.Finally, the pressure loss and the separation efficiency of the two stage cyclone separating device was studied at high-pressure situations with numerical method. The influence of the droplet diameter and the different structure on the pressure loss and the separation efficiency was analyzed. Then the simple optimization of the two stage cyclone separating device was accomplished by summarizing the above results.更多还原