Aiming at the water hammer issues of hydraulic power system wide-body aircraft with 5000 psi pressure system, based on introduction to theory and key components, a complete simulation model is constructed using AMESim software, simulates flow characteristics under transient large conditions. Through verification, current configuration meets standards maximum condition, but does not meet requirements steady state condition. Further improvements can be made by optimizing response speed servo...

As aircraft hydraulic system demands higher pressure, speed, and reliability, the vibration control of pipeline systems becomes more crucial. Aiming to reduce dampen fluid pulsation, stiffness clamps is important improve characteristics systems. This paper proposed a newly designed clamp high stiffness, attenuate vibrations. Modal analysis with finite element simulation employed compare results between traditional P-type clamp, validating effectiveness advantage new clamp.

In order to ensure the installation requirements of aircraft cabin door, double hatch door design adopts form mutual compression differential clearance. that two doors with connection avoid structural damage during process retracting, achieve closing time performance index, and meet system weight hydraulic control system. Through simulation test, it is proved can use, flow-pressure characteristics core components system, such as solenoid valve limiting valve, are obtained. The method has...

A pump-driven actuator, which usually called an electro-hydrostatic actuator (EHA), is widely used in aerospace and industrial applications. It interesting to optimize both its static dynamic performances, such as weight, energy consumption, rise time, stiffness, the design phase. difficult decide parameters, due high number of objectives be taken into consideration simultaneously. This paper proposes a simulation-based multi-objective optimization (MOO) method for EHA with AMESim python...

The flow ripple caused by the hydraulic pump is main source of vibration and noise, so attenuation pressure pulsation significant to control vibration. attenuator with pressurized gas commonly used in industry for broadband cancellation, it also has advantages absorb shock system. A new designed this paper, which can be embedded piston pump, characteristics good compactness versatility. fundamental equations are studied, both time-domain frequency-domain models established. software AMESim...

The reduction of fluid ripple in pipes is extremely important for the reliability and safety aircrafts ships. Currently, most researches only pay attention to discharge port ignore suction inherent characteristic axial pump between both ports, which may cause significant underestimation especially closed-loop hydraulic system. Therefore, aim this study propose a novel passive attenuator, can simultaneously reduce pulsation axial-piston pump, adapt condition frequent change load reversing...

Precipitation change and grazing are the main factors influencing vegetation structure dynamics in semi-arid grassland. However, effects of precipitation variation livestock trampling on seedling emergence patterns plants remain largely unknown. In this study, an experiment with four gradients (no-trampling, light, moderate, heavy) three treatments (ambient precipitation, +30% −30% precipitation) was conducted to assess disturbance annual plants. The results showed that increase...

Hydraulic actuation control system demonstrates instability in several parameter regions. A nonlinear mathematical model of hydraulic rudder airplane is established. Non-dimensional analysis employed to analyze the regions initial Hopf bifurcation which may lead oscillations under effect load. Taking damping coefficient as a reference, load force actuators has great implications on stability. Numerical simulation using ODE solver indicates that stable impacting limit cycle exists at...

With the development of hydraulic system higher pressure and power, fluid borne pulsation in pipelines becomes extremely harmful to whole system. Therefore, control is very significant for improving performance practical systems. The traditional active methods were found be effective, while existing weakness model-based with huge computational consumption poor robustness. A novel method proposed here, using efficient gradient descent algorithm parametric optimization. fast servo valve...

Controlling a 3L-NPC inverter-fed PMSM drive is complicated because of the deviation neutral point voltage. That DC-link voltage not balanced on its upper and lower capacitors tends to result in inaccuracy synthesis expected space vectors. A hybrid SVPWM MPTC method proposed for this problem. Based ratio NP voltage, control strategy includes two stages. Firstly, dwelling time redundant small vectors rearranged as traditional when relatively low. Additionally, with decomposition factor being...

Abstract In the aircraft hydraulic system, constant pressure piston pump, as main power supply component, is widely utilized due to its high efficiency. The flow ripple caused by axial pump may induce pipe vibration and lower components’ reliability, which becomes an especially concerned issue. Compared with traditional relief groove, pre-compression volume (PCV) used in pumps could pre-charge chamber’s reduce backflow more evidently. However, PCV affected system pressure, speed swashplate...

Pumping a large number of groundwater will bring on sea water intrusion in coastal region, and how to use ground-water source heat pump engine prevent invasion is sensitive problem region achieves more attention. This paper takes the engineering progress designing commercial uptown bayu adjacent Liaodong bay Bohai Sea as an example. It introduces simulation which simulates change tendency flow, mass temperature two different schemes well arrangement, anticipates influence by establishing...

The thermal effect in hydraulic circuits becomes a more significant concern, because of the energy demand and management new generation airplane. Although fluid transients pipelines have been researched for decades, is hardly considered. This paper models thermo-fluid characteristics pipe net analytically as well other components, using transfer matrix method (TMM).

Abstract Fluid transients without friction in pipelines can be solved by a time-domain exact solution, using simple recursive process computational grid. However, the calculation time cost of this approach is very high because recursion algorithm. Its improved method, named as fast meshless solution (FMS), was developed to speed up computation introducing time-line interpolation. when considered, conventional distributed model cannot employed directly for FMS meshless. To address problem,...

The baseflow of the Yellow River is vital and important for water resource management understanding hydrological cycle ecohydrology setting in this arid semi-arid basin. This study uses a Lyne Hollick digital filtering technique to investigate behaviors index upper reaches Basin (China). observed streamflow discharges along river were used analyze trend, persistence, periodic characteristics during period 1950–2000. results show that average BFI exhibit decreasing trend will continue decline...

The hydraulic motor is usually controlled by the servo valve, with speed encoder composing a closed loop system. While considering power efficiency, secondary control which changes displacement of always direct method, though response time may be bit longer. For purpose accuracy and method both valve regulation proposed in this paper. Compared traditional valve-controlled system, throttling loss can reduced. simulation using AMESim carried out to verify effectiveness feasibility principle.

The fluid-structure interaction (FSI) can be observed significantly in the axial vibration of liquid-filled pipe system. When distributed friction was neglected, model could solved with an exact solution without numerical error, developed from method characteristics (MOC). Then time-line interpolations have been employed to reduce high time cost and retain accuracy, named as improved solution. For purpose practical applications, series connection double-pipes is discussed this paper. And...