| This paper is part of the research content of the industrial development fund project of Sichuan Province-"Research on Key Technologies of multiphase non-Newtonian fluid solar pumping system for livestock and poultry manure".The actual livestock manure is not only non-Newtonian fluid,but also gas-liquid-solid three-phase non-Newtonian fluid in the pumping process.There are obvious differences between the rotary lobe pump pumping single-phase medium in operating conditions,performance parameters and so on.In the design process,not only the structural and geometric parameters of the rotor,but also the influence of complex medium composition on the operation performance of cam rotor pump must be considered.In order to improve the efficiency and operation stability of the pumping system as much as possible,the flow characteristics of multiphase non-Newtonian fluid pumped by cam rotor pump are studied according to the characteristics of livestock and poultry manure medium.This paper discusses the performance prediction method and parametric optimization design method of rotary lobe pump for pumping livestock and poultry manure,and realizes the optimization design based on the goal of improving operation stability.The main contents and conclusions are as follows:(1)Parametric design and modeling of runner of rotary lobe pump.According to the rotor characteristics of the multi lobe rotary lobe pump,the parametric model of the rotor profile of the rotary lobe pump is constructed,and the integration of the rotor parametric design and calculation of the multi lobe rotary lobe pump and the three-dimensional modeling of the runner of the rotary lobe pump is realized.(2)Study on the relationship between the rheological parameters of poultry manure and the operating performance of rotary lobe pump.According to the rheological characteristics of poultry manure,the liquid phase is simplified to a non Newtonian fluid,numerical simulation analysis the effects of apparent viscosity and power-law index on the operation performance of rotary lobe pump.The results show that with the increase of apparent viscosity,the average flow rate and volumetric efficiency increase gradually,and the pulsation coefficient decreases gradually;With the increase of power law index,the average flow,volumetric efficiency and outlet pulsation coefficient increase gradually.(3)Performance prediction and internal flow characteristics of rotary lobe pump when pumping livestock and poultry manure.Numerical simulation analysis of the effects of different concentrations,gas-solid-liquid composition and operating conditions on performance.The results show that the characteristics of pressure pulsation and the variation law of radial force of rotary lobe pump are mainly affected by the number of rotor blades;With the increase of fecal concentration,the average flow increases and the pulsation coefficient decreases;Gas phase and solid phase components have little influence on the performance of rotary lobe pump,and the relative variation range of average flow and pulsation coefficient is about 1%;With the increase of pressure difference,the outlet flow and volumetric efficiency decrease,and the pulsation coefficient increases relatively;With the increase of rotating speed,the outlet flow increases,the pulsation coefficient decreases and the pulsation amplitude increases.(4)The influence of rotor structure parameters on the performance of pumping livestock and poultry manure is studied,and the rotor structure parameters is optimized.Under the condition of constant rotor diameter,the influence of the main geometric parameters of the rotor structure(length,number of leaves,helix angle)on the performance of rotary lobe pump for pumping livestock and poultry manure was analyzed.With the increase of rotor length,the average flow increases linearly;For the rotary lobe pump demonstration project in this paper,when the rotor length is less than 120 mm,the fluctuation of volumetric efficiency and pulsation coefficient is about 1%;As the number of rotor blades increases,the average flow rate and pulsation coefficient decrease;With the increase of rotor helix angle,the average flow and volumetric efficiency gradually decrease,and the flow pulsation coefficient first decreases and then increases.Based on the comparative analysis of the flow characteristics and pulsation characteristics of different schemes,the rotor flow channel structure is optimized to improve the operation stability.The research results of this subject have been used in the product development of rotary lobe pump in the cooperative enterprise.The developed rotary lobe pump products have been tested and verified by the partner in the factory and used in the actual project,which proves the feasibility of the method and technical route studied in this paper. |
