Research On Fluid Dynamic Characteristics Of Balanced Twin Screw Expander

With the rapid growth of the national economy,the demand for energy is also increasing,and the recycling of resources has been widely concerned.The twin screw expander as a waste heat recovery device,its role is self-evident.However,the existing twin-screw expanders all adopt a three-stage structure design.This structure makes the twin-screw expander rotor subjected to unidirectional axial force during the work process,which has higher requirements on the support parts and is likely to cause excessive wear.As a result,there is a bad condition in the operation of the body,which affects the entire production process.In order to solve the problem of the traditional twin-screw expander to the greatest extent,a balanced twin-screw expander that can eliminate the axial force of the expander rotor is proposed.The structure can balance the unidirectional axial force to solve the problem.Therefore,the research on balanced twin-screw expanders will promote the development of twin-screw expanders and improve the level of industrial equipment.Based on the theoretical basis of twin-screw expander and fluid dynamics theory,this paper studies the establishment of the three-dimensional model of the balanced twin-screw expander,the analysis of internal flow field characteristics and the analysis of the effect of gap leakage on the flow field characteristics.By analyzing the composition characteristics of typical profiles,the XSRM profiles that meet the requirements of this subject are designed according to the design principles of the profiles.Based on the performance study of the twin-screw expander,each zero of the twin-screw rotor and the balanced twin-screw expander is determined.The shape characteristics and geometric parameters of components.After obtaining the relevant parameters,the PROE three-dimensional software is used to construct the three-dimensional model of the rotor and various parts of the balanced twin-screw expander.Based on the shortcomings of the existing working cavity constructed using 3D software,a method of constructing the working cavity using SCORG software is proposed.The working cavity model constructed by this method fully meets the needs of this subject;in order to explore the interior of the balanced twin screw expander The distribution of the fluid in the flow field is based on the constructed flow channel model and the CFX software is used as a solver to calculate the working process of the internal flow field of the balanced twin-screw expander.The pressure,velocity and density of the fluid in the internal flow field are obtained.And the fluid temperature distribution.In order to gain a deeper understanding of the dynamic characteristics of the internal flow field of the balanced twin-screw expander,by analyzing the gap types,it was determined that the gap values of the three main gaps between the tooth gap,the tooth tip gap and the end face gap were variables,and seven experimental combinations were designed.According to the experimental combination,7 types of flow channel models with different gaps were created,and the 7 types of flow channel models were solved with CFX software.Through comparative analysis,the influence of each gap on the internal flow field of the balanced twin-screw expander was obtained.It can be seen from the analysis that among the three types of gaps,the leakage caused by the gap between the teeth has the greatest impact on the balanced twin-screw expander,and the leakage channel caused by it is mainly due to contact line leakage;at the same time,it can also be found that each The gaps also affect each other,and the gap value of the tooth tip gap increases,resulting in a decrease in leakage between the tooth gaps.These studies are of great significance to the research on the optimization of the structure of balanced twin-screw expanders,and provide a basis for engineering practice.