Abstract: The hydraulic spool valve is a critical control component in aerospace hydraulic systems. However, complex working environments can cause the valve core to become stuck, thus severely restricting the performance of such valves. This in turn can hinder the precise control of hydraulic oil, reduce the stability of the hydraulic system, and lead to serious accidents in aerospace systems. The unbalanced radial force and solid particle intrusion into the fit clearance are the main factors behind this sticking. To better understand these issues, in this study, we simulated the fluid dynamics and particle behavior within the clearance of the valve core and analyzed the effects of inclination angle, clearance size, particle diameter, and pressure equalization groove (PEG) properties. The mechanism behind valve core sticking was revealed, and it was found that the PEG has an inhibitory effect on the unbalanced radial force and particle intrusion. Furthermore, we proposed an optimized structure for a triangular pressure equalization groove with an arc-shaped bottom (Tri-PEG). The structural parameters were determined through multi-objective optimization, with the objectives of minimizing the leakage at the clearance and maximizing the particle volume fraction at the bottom of the Tri-PEG. The optimal parameters were an arc-shaped radius of 0.200 mm, a groove depth of 0.392 mm, and a half groove width of 0.215 mm. Comparing Tri-PEG with a rectangular PEG, the leakage was reduced by 12%, and the particle concentration was increased by 6%. Overall, these findings serve as an important reference for alleviating spool valve sticking.

液压滑阀阀芯均压槽非对称间隙流动分析及防卡滞结构优化

[1]AljubranM, HorneR, 2020. Prediction of multilateral inflow control valve flow performance using machine learning. SPE Production Operations, 35(3):691-702.

[2]AmiranteR, DistasoE, TamburranoP, 2016. Sliding spool design for reducing the actuation forces in direct operated proportional directional valves: experimental validation. Energy Conversion and Management, 119:399-410.

[3]ChenQP, LiuM, JiH, et al., 2024. Characterization of hydraulic spool clamping triggered by solid particles based on mechanical model and experiment research. Applied Sciences, 14(19):8880.

[4]ChuYB, YuanZH, HeXG, et al., 2021. Model construction and performance degradation characteristics of a deflector jet pressure servo valve under the condition of oil contamination. International Journal of Aerospace Engineering, 2021:8840084.

[5]DebK, PratapA, AgarwalS, et al., 2002. A fast and elitist multiobjective genetic algorithm: NSGA-II. IEEE Transactions on Evolutionary Computation, 6(2):182-197.

[6]DengWX, ZhouH, ZhouJ, et al., 2023. Neural network-based adaptive asymptotic prescribed performance tracking control of hydraulic manipulators. IEEE Transactions on Systems, Man, and Cybernetics: Systems, 53(1):285-295.

[7]DomagałaM, MomeniH, Domagala-FabisJ, et al., 2018. Simulation of particle erosion in a hydraulic valve. Materials Research Proceedings, 5:17-24.

[8]GaoZX, LiuP, YueY, et al., 2020. Comparison of swing and tilting check valves flowing compressible fluids. Micromachines, 11(8):758.

[9]GuiSY, ZhangSS, FuB, et al., 2022. Fluid-dynamic analysis and multi-objective design optimization of piezoelectric servo valves. Flow Measurement and Instrumentation, 85:102157.

[10]HangLF, GuanAQ, GuXJ, et al., 2026. Effects of throttle groove on viscous heating and thermal deformation of spool valve core. Aerospace Science and Technology, 168:110744.

[11]HongSH, KimKW, 2016. A new type groove for hydraulic spool valve. Tribology International, 103:629-640.

[12]HouFW, ShuHF, WuBB, et al., 2025. Parametric design for the valve seat of a high-temperature and high-pressure valve inside wind tunnels. Journal of Zhejiang University-SCIENCE A, 26(3):266-276.

[13]JiangJH, DuanBS, ZhangJ, et al., 2019. The influence of pressure difference at the valve port of hydraulic throttle cone valve on the luminescence of hydraulic oil. International Journal of Hydromechatronics, 2(2):140-156.

[14]LiHY, LiuJK, LiK, et al., 2021. Development of a high differential pressure piezoelectric active proportional regulation valve using a bending transducer. IEEE Transactions on Industrial Electronics, 68(12):12513-12523.

[15]LiLZ, ZhangYP, TianWX, et al., 2014. MAAP5 simulation of the PWR severe accident induced by pressurizer safety valve stuck-open accident. Progress in Nuclear Energy, 77:141-151.

[16]LiRC, SunYH, WuXW, et al., 2023. Review of the research on and optimization of the flow force of hydraulic spool valves. Processes, 11(7):2183.

[17]LiWD, JiangHP, FengCH, et al., 2025. A hybrid intelligent diagnostic approach for spool jamming faults of hydraulic directional valves. Measurement, 241:115706.

[18]LisowskiE, FiloG, RajdaJ, 2018. Analysis of flow forces in the initial phase of throttle gap opening in a proportional control valve. Flow Measurement and Instrumentation, 59:157-167.

[19]LiuXQ, JiH, MinW, et al., 2020. Erosion behavior and influence of solid particles in hydraulic spool valve without notches. Engineering Failure Analysis, 108:104262.

[20]LuL, WangJ, LiMR, et al., 2022. Experimental and numerical analysis on vortex cavitation morphological characteristics in U-shape notch spool valve and the vortex cavitation coupled choked flow conditions. International Journal of Heat and Mass Transfer, 189:122707.

[21]MittalR, IaccarinoG, 2005. Immersed boundary methods. Annual Review of Fluid Mechanics, 37:239-261.

[22]QianJY, LiuBZ, LeiLN, et al., 2016. Effects of orifice on pressure difference in pilot-control globe valve by experimental and numerical methods. International Journal of Hydrogen Energy, 41(41):18562-18570.

[23]QianJY, MuJ, HouCW, et al., 2021. A parametric study on unbalanced moment of piston type valve core. Journal of Zhejiang University-SCIENCE A, 22(4):265-276.

[24]QianJY, XuJX, ZhongFP, et al., 2023. Solid-liquid flow characteristics and sticking-force analysis of valve-core fitting clearance. Journal of Zhejiang University-SCIENCE A, 24(12):1096-1105.

[25]ShanbhagVV, MeyerTJJ, CaspersLW, et al., 2021. Failure monitoring and predictive maintenance of hydraulic cylinder—state-of-the-art review. IEEE/ASME Transactions on Mechatronics, 26(6):3087-3103.

[26]ShiX, ChaiYY, ChenH, et al., 2024. Numerical simulation of pressure loss and flow characteristics in combined elbow pipes for solid-liquid two-phase flow. Water Science Technology, 90(4):1099-1114.

[27]SunF, XuH, ChengM, et al., 2021. Sensitive monitoring particles conveying in water hydraulic system via a facile molding conductive hydrogel. IEEE Sensors Journal, 21(9):10506-10513.

[28]SunZC, AnT, QianZL, et al., 2026. Reliability of valves in nuclear power plant: a review of full life-cycle frameworks and evolution toward physics-data fusion. Journal of Reliability Science and Engineering, 2(1):012001.

[29]TerrellEJ, HiggsIII CF, 2007. A modeling approach for predicting the abrasive particle motion during chemical mechanical polishing. Journal of Tribology, 129(4):933-941.

[30]WangGM, XueLJ, ZhuYF, et al., 2023. Fault diagnosis of power-shift system in continuously variable transmission tractors based on improved echo state network. Engineering Applications of Artificial Intelligence, 126:106852.

[31]WangZT, LiWQ, WangXH, et al., 2026. Design of asymmetric combined flow-guiding valve core structure in hydraulic spool valve. Annals of Nuclear Energy, 227:11938.

[32]YinYB, YuanJY, GuoSR, 2017. Numerical study of solid particle erosion in hydraulic spool valves. Wear, 392-393:174-189.

[33]ZhangJ, DuRH, DongPP, et al., 2025. Effect of slide valve gap surface roughness on particle transport properties. Aerospace, 12(7):608.

[34]ZhangSZ, LinZH, ChenSJ, et al., 2024. Unbalanced force analysis on valve core clamping in hydraulic spool valves. Annals of Nuclear Energy, 203:110505.

[35]ZhangXL, WangAL, ChenW, et al., 2020. Methodology for expressing the flow coefficients of coupled throttling grooves in a proportional—directional valve. Journal of Zhejiang University-SCIENCE A, 21(10):799-816.

[36]ZhangYH, DingBC, ZhengSP, et al., 2025. Radial flow force reduction in a hydraulic spool valve using balanced through-hole design. Physics of Fluids, 37(9):095114.

[37]ZhaoRH, LiaoYY, LianZS, et al., 2021. Research on the performance of a novel electro-hydraulic proportional directional valve with position-feedback groove. Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, 235(6):1930-1944.

[38]ZhengN, TongBH, YangW, et al., 2020. Study on pressure balance and clearance flow characteristics of composite-grooved piston–copper pair. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 42(6):286.

[39]ZhongQ, BaoHM, LiYB, et al., 2021. Investigation into the independent metering control performance of a twin spools valve with switching technology-controlled pilot stage. Chinese Journal of Mechanical Engineering, 34(1):91.

[40]ZhuXG, LiuPF, LuanJH, et al., 2026. Key technologies and engineering applications of digital simulation for reliability of aerospace products. Journal of Reliability Science and Engineering, 2(1):015201.