Analysis of the Internal Characteristics of a Deflector Jet Servo Valve

Abstract

In current research on deflector jet servo valves, the receiver pressure estimated using traditional two-dimensional simulation and theoretical calculation is always lower than the experimental data; therefore, credible information about the flow field in the prestage part of the valve can hardly be obtained. To investigate this issue and understand the internal characteristics of the deflector jet valve, a realistic numerical model is constructed and a three-dimensional simulation carried out that displays a complex flow pattern in the deflector jet structure. Then six phases of the flow pattern are presented, and the defects of the two-dimensional simulation are revealed. Based on the simulation results, it is found that the jet in the deflector has a longer core area and the fluid near the shunt wedge cannot resist the impact of the high-speed fluid. Therefore, two assumptions about the flow distribution are presented by which to construct a more complete theoretical model. The receiver pressure and prestage pressure gain are significantly enhanced in the calculations. Finally, special experiments on the prestage of the servo valve are performed, and the pressure performance of the numerical simulation and the theoretical calculation agree well with the experimental data. Finally, the internal mechanism described by the theoretical and numerical models is verified. From this research, more accurate numerical and theoretical models are proposed by which to figure out the internal characteristics of the deflector jet valve.

Numerical Study on Flow-Induced Noise of Deflector Jet Servo Valve Based on LES/Lighthill Hybrid Method

“…Oil flows into the prestage from the pressure inlet, forming two jet processes [28]. e pressure and velocity distributions are shown in Figure 10.…”

Novel resonance stability criterion for the 2D magnetically levitated servo-proportional valve

“…16,17 To increase the dynamic response and still maintain susceptibility to contamination, the deflector-jet valve appears and replaces jet pipe valve gradually. 18 Some servo valves are actuated by a moving coil motor with very large exciting current, which is called as the moving coil valve. 19 People also put forward novel pilot operated configurations to further improve the performance of the servo valve.…”

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

“…However, since the pilot stage is the core component of the DJSV and the energy transfer process and flow field structure is very complex, there still many unsolved questions [11] . Scholars have carried out many studies in the pilot stage modeling [12][13][14][15][16] , flow force calculation [17,18] , cavitation [19] and application of new materials [20,21] on the DJSV and got rich research achievements. For example, Yin et al built a simplified model to calculate pressure characteristic based on Bernoulli equation and analyzed the null shift when the pilot stage structure is not symmetrical [12] ; Yan et al established a two-dimensional(2D) model about •3• internal flow field of pilot stage, and obtained the steadystate fluid force by the momentum principle method and the differential pressure method based on the simulated discrete data [16] ; B K Saha and Li researched the cavitation phenomena inside the pilot stage through experimental flow visualization and numerical investigations, the attached cloud-like cavitation or bubble shedding is observed and identified the significant locations of cavitation [19] ; D K Sangiah and Y C Zhu developed the deflector servo valve driven by the bimorph rectangular actuator and the giant magnetostrictive actuator respectively [20,21] , and analyzed the static and dynamic characteristics of the servo valve.…”

“…In the third method, the rectangular jet is regarded as a plane jet with a certain thickness, which is equal to the thickness of the jet-pan. On this basis, the pressure characteristics and flow characteristics are modeled, but the entrainment of the jet in the third dimension is also ignored [15,16] . In terms of research objects, since typical jet nozzle, guide groove and receiving chamber of the pilot stage are rectangular, the model calculation method based on axisymmetric jet is not suitable for most DJSV and has no general significance.…”