Research On Asymmetric Flow Resistance Valve Based On Bluff Body Structure

Traditional asymmetric flow resistance structure which mainly consists of hydraulic valve and damping may lead to negative influence on hydraulic system as complex connection pipe and vulnerable hydraulic valve.No-moving parts valves in this paper take asymmetric flow resistance structure as spool,that means the spools of the valves are motionless so that spool wear is reduced and response characteristic of the valves could be ignored.In addition,the valves could reduce requirement on cleanliness of fluid as small particles of fluid have no impact on the valves.The structure of the valve could be simplified and miniaturized,that expands application areas of the valve.Based on the analysis of relevant literature,the dissertation mainly focuses on the following contents:Based on the principle that fluid flowed around a asymmetric object could result different pressure drop,rhombus asymmetric flow resistance structure which consisted of several semi-cylindrical shells was proposed and relevant mathematical model was built;Numerical simulation technique was adopted to research influence that structure parameters had on rhombus asymmetric flow resistance structure,that provided theoretical guidance for experiment;Experiment system was built and experimental research was performed on asymmetric flow resistance valve whose spool was bluff body structure.The experimental results coincide with the simulation results and then verify the correctness of numerical calculation model.Asymmetric flow resistance valve was used in impact test system.The main contents of each chapter are as follows:Chapter.1 introduced the research background of the project.Present of the study including no-moving parts valve?influence of channel structure on flow resistance and CFD technology were briefly summarized.Chapter.2 introduce flow around a bluff body and principle of different pressure.asymmetric flow resistance valve was introduced including valve's theory and basic structure that was asymmetric flow resistance structure.Semi-cylindrical shell was adopted as basic component of structure.Flow around a single Semi-cylindrical shell was analyzed qualitatively from the perspective of stress and the reasonability of taking the pressure drop ratio as a measure of structure's performance was expounded.Chapter.3 introduced numerical mathematical model according to fundamental equations of fluid mechanics and CFD theory.CFD codes CFX were used in numerical simulations of flow around a single semi-cylindrical shell to verify the conclusion of theoretical analysis.The influence which relative position of bluff body have on flow resistance characteristic was analyzed,that could guide research on multiple blunt body arrangement.Rhombus asymmetric flow resistance structure was proposed,and was simulated which indicated the change of flow field.Chapter.4 took rhombus asymmetric flow resistance structure as research target,that explored to get the parameters that influence the performance of the structure.Chapter.5 introduced the valve's structure that adopted rhombus asymmetric flow resistance structure as spool.Based on the conclusions gained with numerical simulation,geometrical parameters were defined and experiments were conducted to research the flow resistance characteristic.Chapter.6 summarized main work of the project and provided an outlook of the further research directions.