Flow Field Analysis And Dynamic Performance Study Of Twin Screw Expander

Twin-screw expander is anew device with unique characteristics.In our country,its appearance can save energy greatly,reduce maintenance time and replace inports in the use process,besides it can realize the reuse of energy and inprove economic efficiency.At the same tine,the use of it can also reduces the noise pollution in the working process.In the world,the development and use of twin screw expanders to replace various traditional expanders has become an inevitable trend in the devel-opment of science and technology.,which provides a broad space for utilizing screw expander to recover waste heat and generate electricity.Therefore,it has certain theoretical significance and im-portant practical value to optimize and improve the existing twin-screw expander and to research and develop high-performance industrial twin-screw expander.In view of this,the twin screw expander is analyzed and studied under the following aspects(1)Driving Test and Profile Improvement of Twin Screw ExpanderWith conpressed air as the medium,a test platform for the dynamic performance of twin-screw expander was designed and built.The basic dynamic perfornance test of twin-screw expander was conpleted,and the working efficiency of twin-screw expander was obtained.Through the analysis of experinental results,based on the characteristics of some typical profiles,the single-sided asymmetric cycloid-pin circular arc profiles are improved,some characteristics of the original profiles are retained,and NURBS curve is introduced into the type of tooth profiles to inprove the adjustability and adapt-ability of the rotor profiles,and the general equation of the inproved profiles is derived.Finally,the phase of the inproved profiles is analyzed.A new type of rotor profile is obtained with respect to the performance parameters.Based on matlab,a user interfece program for rapid drawing of profile is designed,which facilitates rapid three-dimensional modeling for subsequent structural optimization,and provides an effective tool for structural optimization of twin screw expander.(2)Flow field and mechanical analysis of twin screw expanderCFX in ANSYS is used to analyze the flow field of twin-screw expander.The distribution of velocity field and tenperature field of the expander is obtained by setting its relevant parameters.By setting the contact modes and relevant constraints between the parts,the load is loaded on the helical surface of the Yin-Yang rotor by directly loading the fluid force on the Yin-Yang rotor obtained from the above-mentioned flow field analysis on the screw helical surface.The dynamics of the nioving components of the twin-screw expander is studied.The axial and radial deformation diagrams of the screw rotor are obtained by tumerical simulation.The stress and deformation model of the screw is constructed based on the change curve of the maximum deformed joint in these two directions,which can provide reference for optimizing and inproving the clearance between the Yin and Yang rotors and between the rotor and the shell.(3)Modal and Harmonic Response Analysis of Twin Screw ExpanderEstablish the mathematical model of Twin Screw Expander,The free mode analysis of the twin screw expander is carried out,and its natural frequencies and corresponding main modes are obtained;Secondly,the constrained modes are set to obtain the natural frequencies and the corresponding min modes of the constrained modes.Conparisons the modal analysis results between free and con-strained States,When the external excitation frequency avoids the natural frequency of the rotor,the rotor can operate steadily and reliably.Then the harmonic response of the expander is analyzed to study its continuous dynamic eharacteristics under a harmonic load of a specific frequency.The radial deformation and angular displacement of the expander moving corrponent are analyzed.The nodal analysis and harmonic response analysis provide a reference for the design and optimization of the Yin-Yang rotor.