CFD investigations of flow field and cavitation phenomena in the pilot stage of deflector jet servo-valve

2019 ◽  
Author(s):  
Bijan Krishna Saha ◽  
Lujia Li ◽  
Songjing Li
Keyword(s):  
Flow Field ◽  
Servo Valve ◽  
Deflector Jet

scholarly journals Analysis of Three-Dimensional Flow Field Inside the Pilot Stage of the Deflector Jet Servo Valve

2021 ◽  
Author(s):  
Shuanglu Li ◽  
YaoBao Yin ◽  
JiaYang Yuan ◽  
ShengRong Guo
Keyword(s):  
Flow Field ◽  
Field Model ◽  
Structural Parameters ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Static Characteristics ◽  
Servo Valve ◽  
Free Jet ◽  
Dimensional Flow ◽  
Deflector Jet

Abstract Current two-dimensional flow field model has some defects in describing the pilot stage’s flow field and static characteristics of the deflector jet servo valve(DJSV) because the three-dimensional(3D) jet of the flow field is ignored. In order to overcome the shortcomings, a new flow field model is proposed and the energy transfer process of the pilot stage is obtained. In this model, the flow field is divided into five regions: pressure jet region, free jet region, mixed collision region, secondary jet region and pressure recovery region. Especially, three-dimensional turbulent jet is adopted in the free jet region for the first time to describe the structure of the flow field, and the jet entrainment model is proposed in pressure recovery region to describe the coupling relationship between the pressure in the receiving chamber and the jet flow which has never been considered before. The static characteristics of the pilot stage, such as pressure-flow characteristics, pressure characteristics and flow characteristics are obtained, and the relationship between zero-position valve coefficients and the key structural parameters of the pilot stage is analyzed. The results show that main structural parameters that affect the pressure gain include the length of receiving chamber, the width of guide groove outlet and the width of the wedge; The thickness of jet-pan has the most significant influence on flow gain. The flow field structure and the static characteristics are verified respectively by finite element analysis(FEA) and experimental results, and the results show that the pilot stage mathematical model has good reliability which is beneficial to understand the working mechanism of the pilot stage provide theoretical basis for parameter optimization.

Visualization of Flow-Field between the Flapper and Nozzle in a Hydraulic Servo-Valve

2011 ◽  
Vol 402 ◽  
pp. 407-411 ◽  
Author(s):  
Jacob M. Mchenya ◽  
Sheng Zhuo Zhang ◽  
Song Jing Li
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Video Camera ◽  
Computer Assisted ◽  
Servo Valve ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Hydraulic Servo ◽  
Working Principle ◽  
Computer Assisted Image

In order to understand the mechanism and get rid of the high-frequency self-excited noise in a hydraulic servo-valve, in this paper, the flow field distribution in the pilot stage of a hydraulic flapper-nozzle servo-valve is investigated. An assembly is prepared representing the construction and working principle of the flow field inside the pilot stage of a hydraulic flapper-nozzle servo-valve. A method of visualization is developed by taking videos for the flow field inside the transparent assembly with a high speed video camera. In this study, at different inlet pressure the high speed video camera was utilized for flow visualization together with computer-assisted image measurement. The shape of the jet flow, the cavitations and vortex flow inside the flow field can be visualized clearly. The proposed method enables to analyze the flow-field in the pilot stage of a hydraulic flapper-nozzle servo-valve by giving useful information for better design.

The Research of the Servovalve Noise

2013 ◽  
Vol 706-708 ◽  
pp. 1639-1643 ◽  
Author(s):  
Yuan Zhang Chen ◽  
Da Ping Gong
Keyword(s):  
Flow Field ◽  
Internal Structure ◽  
Field Distribution ◽  
Negative Pressure ◽  
Cfd Simulation ◽  
Pressure Change ◽  
Servo Valve ◽  
Pressure Zone ◽  
Circuit Structure ◽  
Pressure Area

Use Gambit and Fluent to the servo valve armature component of squeak problem undertook CFD is analyzed, simulates the flow field distribution in internal circuit structure, found in the servo valve armature component whistle when fluid in the inner of the product, produced a marked a negative pressure zone, and in this context the armature assembly stress sharply change, causing the armature assembly vibration squeal, changing the internal structure of the product again CFD simulation, negative pressure area disappeared, the pressure change tends to be steady, the structure of the product was the actual through pressure liquid servo valve test, howling problem solved.

scholarly journals Analysis of the Internal Characteristics of a Deflector Jet Servo Valve

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Hao Yan ◽  
Yukai Ren ◽  
Lei Yao ◽  
Lijing Dong
Keyword(s):  
Servo Valve ◽  
Deflector Jet

scholarly journals Model Construction and Performance Degradation Characteristics of a Deflector Jet Pressure Servo Valve under the Condition of Oil Contamination

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yuanbo Chu ◽  
Zhaohui Yuan ◽  
Xuegong He ◽  
Zhichao Dong
Keyword(s):  
Failure Modes ◽  
Structural Characteristics ◽  
Slide Valve ◽  
Performance Degradation ◽  
Dynamics Simulation ◽  
Oil Contamination ◽  
Characteristic Analysis ◽  
Servo Valve ◽  
Output Pressure ◽  
Deflector Jet

The deflector jet pressure servo valve is a kind of high-precision hydraulic component that can be widely used in the antiskid braking system of an aircraft. In actual service, it will be faced with extreme working conditions of gradual oil contamination, which will cause performance degradation and function maladjustment of the whole valve. To this end, the paper proposes a performance degradation characteristic analysis method. In which, firstly, the structural characteristics and working principle of the deflector jet pressure valve are analyzed; then, the entire dynamics model of the pressure valve is built using the braking cavity as the load blind cavity. Secondly, the two main failure modes induced by oil contamination such as erosion wear of pilot stage and stuck of slide valve stage’s valve core are determined based on the engineering experience, aimed at which the failure mechanism is analyzed; then, the sensitivity simulation model of the servo valve’s output pressure with respect to key degradation parameters is established and the sensitivity analysis is performed. Finally, combining the theoretical analysis with multiphysics simulation correction methods, the performance degradation model of the typical failure modes are established, and then, the performance degradation characteristics under dynamic contamination conditions are analyzed, which is combined with the failure threshold determined by the dynamics simulation to finish the service life prediction of the deflector jet servo valve.

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