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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2022 Vol.23 No.10 P.795-806
Three-dimensional flow field mathematical model inside the pilot stage of the deflector jet servo valve
Abstract: A new flow field mathematical model is proposed to describe accurately the flow field structure and calculate the static characteristics of the pilot stage in a deflector jet servo valve (DJSV). The flow field is divided into five regions, a 3D turbulent jet is adopted to describe the free jet region, and a velocity distribution expression of the jet is proposed. The jet entrainment model is put forward in the pressure recovery region to describe the coupling relationship between the pressure in the receiving chamber and the jet flow. The static characteristics, including pressure-flow characteristics, pressure characteristics, and flow characteristics of the pilot stage are obtained. The flow field structure and the static characteristics are verified by finite element analysis (FEA) and experiment, respectively, and the mathematical model results are in good agreement with the experimental and simulation results.
Key words: Deflector jet servo valve (DJSV); Pilot stage; Three-dimensional jets; Jets entrainment; Static characteristics; Mathematical model
机构：1同济大学，机械与能源工程学院，中国上海，201804；2中航工业航空机电系统综合航空科技重点实验室，中国南京，210061
目的：偏转板伺服阀前置级二维流场模型因忽略了射流在射流盘厚度上的拓展现象，无法准确地描述偏转板伺服阀前置级流场结构。为了更加精确地描述流场结构并计算前置级的静态特性，并有利于优化偏转板伺服阀前置级的结构参数，本文提出一个符合真实状态的三维流场数学模型。
创新点：1.在前置级三维流场数学模型中，将流场分为五个区域，考虑射流在空间上的三维拓展。2.运用三维紊动射流描述自由射流区流场结构，并提出该区域的射流速度分布表达式。3.在压力恢复区提出射流卷吸模型，并建立起接收腔射流流量和恢复压力的耦合关系。
方法：1.通过理论分析，建立前置级流场各阶段的数学模型（图2~9），得到前置级静态特性的理论分析方法（图11和12）；2.通过实验研究某型前置级在不同供油压力下的断载压力特性，验证本文提出的数学模型在计算静态特性时的准确性（图15）；3.通过仿真模拟，分析前置级自由射流区射流截面的速度分布以及接收腔内的射流影响因素，验证三维射流模型和射流卷吸模型的可行性和有效性（图17）。
结论：1.前置级流场内的射流属于三维射流。本文采用的三维射流可以更加准确地描述流场的结构（图2）。2.自由射流区的等速度线接近直槽口形，可近似用矩形等速度线描述（图17），并且接收腔内的射流流量和恢复压力等参数存在耦合关系，可以用本文提出的卷吸射流模型描述。3.在不同供油压力下的前置级无因次断载压力基本一致，基于三维流场模型得到的前置级静态方法计算结果准确（图15），可以为前置级的结构优化提供理论支持。
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DOI:
10.1631/jzus.A2200030
CLC number:
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On-line Access:
2022-10-20
Received:
2022-01-18
Revision Accepted:
2022-07-11
Crosschecked:
2022-10-21