Jin-yuan QIAN ,Wei WU ,Min CHENG ,Jun-hui ZHANG

1Institute of Process Equipment,College of Energy Engineering,Zhejiang University,Hangzhou 310027,China

2School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China

3School of Mechanical and Vehicle Engineering,Chongqing University,Chongqing 400044,China

4Institute of Mechatronics and Control Engineering,Zhejiang University,Hangzhou 310027,China

5State Key Laboratory of Fluid Power and Mechatronic Systems,Zhejiang University,Hangzhou 310027,China

Introduction

The usual metaphors of“heart”and“throat”indi‐cate the importance of pumps and valves in industrial systems including petroleum,chemical,metallurgy,aviation,and aerospace.With the continuous penetra‐tion of the industrial internet,the miniaturization,digi‐tization,multi-functionalization,and systemization of valves have become very important (Si et al.,2020;Chang et al.,2021;Pang et al.,2021;Bonilla et al.,2022;Yuan et al.,2022;Zhao et al.,2022).Flow con‐trol,especially smart flow control,is one of the criti‐cal issues in the field of pump and valve research re‐lated to the process requirements of piping systems(Jin et al.,2020;Lyu LT et al.,2021;Fiderek et al.,2022;Zhang et al.,2022).The importance of smart flow control is greatly increased when valves operate at high temperatures and in high-pressure environ‐ments,or in novel fluids such as nanofluids,com‐pressed hydrogen,and superheated steam(Qian et al.,2020a,2020b;Ji et al.,2021;Lin et al.,2021;Lyu F et al.,2021).Online fault detection is an important means of intelligent operation and maintenance of pumps and valves;it not only ensures their perfor‐mance requirements,but also prolongs their service life (di Capaci and Scali,2018;Zhou et al.,2018;Tang et al.,2019;Yu et al.,2020;Vailati and Gold‐farb,2021;Pedersen et al.,2022;Peng et al.,2022).Therefore,it is urgent to develop intelligent valves with adjustment accuracy,fast response,accurate parameter feedback,convenient remote operation,instant online fault diagnosis,and fail-safe capability.As this field has attracted more and more attention in recent years,it has achieved remarkable development.However,it is worth noting that there is no dedicated publication or issue devoted to these aspects.

This special issue contains original and hitherto unpublished work on the practice of flow control and smart valves.Focal points of the issue include,but are not limited to,innovative applications of:(1) opti‐mized design of novel valve cores,valve bodies,and flow channels;(2) improved precise control of flow,valve target pressure,and reduction of noise and vi‐bration in piping systems;(3) development of novel fluid valves for use with nanofluids,superheated steam,pressurized hydrogen,and so on;(4) develop‐ment of sensing systems for parameter feedback,re‐mote operation,and fault diagnosis.

We have invited renowned scientists in the field to share their expertise and perspectives.These cover the various topics mentioned:(1) on-line fault diag‐nosis of pumps and valves;(2) on-line performance monitoring of pumps and valves;(3) improvement of pumps and valves under extreme conditions,in re‐spect of dynamic performance,seal performance,and adjustment accuracy.

Lin et al.(2022)analyze the seal performance of hydrogenated nitrile butadiene rubber (HNBR) gaskets in a charge valve seal pair by finite element analysis.A nonlinear finite element analysis model is established to dynamically analyze the seal contact characteristics under different pre-compression amounts,seal widths,and hydrogen pressures.The contact pressure on the sealing surface increases with the increase in precompression.When the seal width increases,so does the contact pressure on the seal faces and the width of the separation area between the seal faces.

Shi et al.(2022) propose a heterogeneous sensor information fusion method to enhance the fault ex‐pression ability of the feature set,so that the diversifi‐cation of fault types (electromagnetic faults and me‐chanical faults) can be characterized.The personal‐ized weighting method (using the entropy weighting method and attention mechanism) used in the article enhances the effective signal and weakens the interfer‐ence source.This method can achieve a higher fault diagnosis accuracy under severe working conditions.

Zhong et al.(2022) propose an on/off pilot tech‐nique using two independent high-speed on/off valves(HSVs)to replace conventional pilot-operated propor‐tional valves.Through the fast-switching characteris‐tics of HSV,the dead zone of the pilot stage is avoided,and the dynamic response performance of the main valve is improved.The feasibility of switching the pilot technology scheme is proved through theoretical analysis and experimental demonstration.

Kang et al.(2022) use a whole-valve transfer function model to analyze the mechanism and evalua‐tion of the operating point drift when a thermal effect acts on the servo valve.The asymmetrical relation‐ship of the armature-nozzle combination is an impor‐tant reason for the thermal effect causing drift of the operating point.Differences in structural parameters and fluid medium properties at different temperatures lead to nonlinear changes in the operating point.

Sun et al.(2022)propose a fault diagnosis method based on mathematical model(MM)imputation and a modified deep residual shrinking network (MDRSN),which improves the accuracy in missing data estima‐tion and fault diagnosis.Multiple fault time-series samples of the regulating valve at different opening degrees are collected.The MM imputation model is used to supplement the incomplete data set,and an improved residual shrinkage network is used to diag‐nose the faults of the control valve under different conditions.

Lu et al.(2022) analyze the statically indetermi‐nate structure of an unloading valve and quantitatively calculate the amount of fretting wear of a valve in a gasoline direct injection high-pressure pump.A fret‐ting wear test system is constructed,and the test data of ball valve fretting wear is obtained.Through theo‐retical derivation,a statically indeterminate force model of ball valve fretting wear is constructed,and the key fretting parameters required for simulation calculation are obtained.The wear formula suitable for finite element calculation is obtained by improv‐ing the Archard wear model,and a quantitative nu‐merical calculation model of ball valve fretting wear is constructed by combining the iterative acceleration calculation method and grid adaptive technology.

Mao et al.(2022) propose a single-layer and stacked electrohydrodynamic (EHD) pump to im‐prove the output pressure and flow of an electric hy‐draulic pump.The bendable and twistable electrohydraulic pump is realized by digital manufacturing,and the designed and processed electro-hydraulic pump is used to drive the eccentric actuator.The output pres‐sure and flow of the superimposed electric hydraulic pump are measured experimentally and compared with the output pressure and flow of a single-layer electric hydraulic pump.

We believe this special issue will provide a forum for researchers and engineers to present and discuss recent developments in the practice of flow control and smart valves.We expect the selected papers will stimulate discussion among scientific researchers,and we hope that they will bring new inspiration to read‐ers of this journal.

Conflict of interest

Jin-yuan QIAN,Wei WU,Min CHENG,and Jun-hui ZHANG declare that they have no conflict of interest.