Deep-sea hydraulic systems, powering a wide range of numerous deep-sea operating equipment, employ many poppet valves to adjust the pressure and flow rate, thereby realizing precise movements of the actuators. With greater depths and ambient pressures, the hydraulic oil viscosity increases exponentially, leading to a significant difference in the performance of the poppet valve compared to on-land usage and across varying depths. Based on the shear stress transport (SST) k-ω turbulence model and the dynamic mesh method, a computational fluid dynamics (CFD) model of the poppet valve was established. With the viscosity–pressure characteristics considered, the performance of the poppet valve was analyzed under different depths, different inlet flow rates, and different cracking pressures. The results indicate significant performance deterioration in poppet valves at increased depths, characterized by increased pressure loss and extended response rise time. At 11 km underwater, the pressure loss can be 7 MPa larger than the preset cracking pressure of 10 MPa, and the rise time is doubled compared with the land condition. It is recommended to use hydraulic oils with a lower initial viscosity and a slower increase in viscosity with pressure in deep sea conditions.

Gas-Dynamic Features of Stationary Air Flow Admission into a Cylinder Through a Poppet Valve and Cross Profiled Channels

Cavitation evolution mechanism and periodic flow of aviation pressure poppet valve

The emulsion pump’s flow loss directly affects its performance and efficiency. However, the annular plunger chamber leakage and valve core hysteresis are challenging to avoid during operation. This study systematically investigated the impact of the annular gap in the plunger cavity on emulsion pump performance. Using theoretical analysis and computational fluid dynamics methods, it explored the mechanism of the port valve hysteresis during discharge. The simulation results show that the leakage of the annular gap is proportional to the gap thickness and the inlet pressure and inversely proportional to the dynamic viscosity of the emulsion. With the increase of plunger eccentricity, the leakage increases slowly. The increase in the outlet diameter of the port valve will lead to more significant hysteresis of the valve core. The change of outlet pressure has little effect on the hysteresis and flow of the spool, and the response speed of the wing-guided bevel discharge valve is faster than that of the ordinary poppet valve. Considering the above factors, the flow distribution process of the emulsion pump can be accurately analyzed, providing a reference for pump optimization.

A significant challenge in utilizing hydrogen in conventional internal combustion engines is achieving a balance between NOx emissions and brake power output. A lean premixed charge (Lambda ≈ 2.5) allows for efficient and stable combustion with minimal NOx emissions. However, this comes at the cost of reduced power density due to the higher air requirements of the thermodynamic process. While supercharging can mitigate this drawback, it introduces increased complexity, cost, and size. An intriguing alternative is the 2-stroke cycle, particularly in an opposed piston (OP) configuration. This study presents the virtual development of a single-cylinder 2-stroke OP engine with a total displacement of 0.95 L, designed to deliver 25 kW at 3000 rpm. Thanks to its compact size, high thermal efficiency, robustness, modularity, and low manufacturing cost, this engine is intended for use either as an industrial power unit or in combination with electric motors in hybrid vehicles. The overarching goal of this project is to demonstrate that internal combustion engines can offer a practical and cost-effective alternative to hydrogen fuel cells without significant penalties in terms of efficiency and pollutant emissions. The design of this novel engine started from scratch, and both 1D and 3D CFD simulations were employed, with particular focus on optimizing the cylinder’s geometry and developing an efficient low-pressure injection system. The numerical methodology was based on state-of-the-art commercial codes, in line with established engineering practices. The numerical results indicated that the optimized engine configuration slightly surpasses the target performance, achieving 29 kW at 3000 rpm, while maintaining near-zero NOx emissions (<20 ppm) and high brake thermal efficiency (~40%) over a wide power range. Additionally, the cost of this engine is projected to be lower than an equivalent 4-stroke engine, due to fewer components (e.g., no cylinder head, poppet valves, or camshafts) and a lighter construction.

The necessity for greater energy conservation in hydraulic machinery is highlighted by escalating fuel costs and heightened ecological awareness. Utilizing independent metering to enhance the energy utilization of hydraulic actuators is one effective strategy, yet the market is short on efficient reversible proportional valves that can perform this function. For handling modest flow rates up to 150 Liters per minute, the digital hydraulic method utilizing fast direct operated on/off solenoid valves shows promise; however, solutions for managing larger flows remain vague. This research explores the application of pilot-operated solenoid valves in digital hydraulic systems designed for substantial flow volumes. It establishes a model grounded in physical principles to examine how various factors influence the valve reaction speed. A unique valve design was established, derived from an existing valve but with a modified structure. The findings indicate that the pressure difference, viscosity of the fluid and pilot plunger dynamics are crucial determinants of the valve response time. Incorporating a stroke limiter proves significant in harmonizing the response times across valves with varying flow rates, while the traditional methods of deploying serial orifices is deemed unsuitable. A glance from the results shows that at a ΔP of 10 bar, the valve with an 8 mm attached serial orifice has an opening response of 65 ms, while the stroke limited valve achieves 40 ms. This significant advantage slightly narrows at higher pressures, stabilizing at 100 bar. During closing, the stroke limiter is remarkably 60% faster at 10bar, and both configurations settle at 40 ms at 200 bar.

Gas exchange optimization in aircraft engines using sustainable aviation fuel: A design of experiment and genetic algorithm approach

Abstract The large flow rate proportional poppet valve (PPV) finds widespread use in high‐power hydraulic systems. However, the indispensable dead‐zone nonlinearity that guarantees the safe shut‐off of the PPV will cause a tracking lag when a command goes outside the dead‐zone. The lag should be properly solved in a controller, which is a highlight of this study. Simultaneously, achieving high tracking precision in a PPV is necessary to meet the demands of advanced hydraulic systems. In this study, a practical nonlinear controller based on an integral separated disturbance observer is proposed to improve the performance of a PPV. In particular, the lag could be alleviated and the high tracking precision achieved simultaneously by enabling or disabling a disturbance observer in the proposed controller. A separation coefficient is proposed for the disturbance observer to detach the integral action from the controller and avert the deep input saturation of the pilot stage. Additionally, the command filtering technology is applied to the nonlinear controller to improve its interference resisting capacity in the industrial environment. The stability and effectiveness of the proposed controller are proved in theory and verified by experiments.

Geometrical transition properties of vortex cavitation and associated flow-choking characteristics in poppet valves

A novel magnetic actuated ultra-clean poppet valve and its dynamic characteristics analysis

Theoretical model for high-altitude gas exchange process in multi-fuel poppet valves two-stroke aircraft engine

Experimental Assessment of Flow Structure in a Cylinder During Air Flow Through Poppet Valves of Different Configurations

Design of motor driver circuit for unconstrained poppet valve and its implementation to flexible circuit

Impact of medium-pressure direct injection in a spark-ignition engine fueled by hydrogen

A detailed study of the gas-dynamic behaviour of both liquid and gas flows is urgently required for a variety of technical and process design applications. This article provides an overview of the application and an improvement to thermal anemometry methods and tools. The principle and advantages of a hot-wire anemometer operating according to the constant-temperature method are described. An original electronic circuit for a constant-temperature hot-wire anemometer with a filament protection unit is proposed for measuring the instantaneous velocity values of both stationary and pulsating gas flows in pipelines. The filament protection unit increases the measuring system's reliability. The designs of the hot-wire anemometer and filament sensor are described. Based on development tests, the correct functioning of the measuring system was confirmed, and the main technical specifications (the time constant and calibration curve) were determined. A measuring system for determining instantaneous gas flow velocity values with a time constant from 0.5 to 3.0 ms and a relative uncertainty of 5.1% is proposed. Based on pilot studies of stationary and pulsating gas flows in different gas-dynamic systems (a straight pipeline, a curved channel, a system with a poppet valve or a damper, and the external influence on the flow), the applications of the hot-wire anemometer and sensor are identified.

The purpose of the article is to extend the operational life of piston pumps by making beneficial modifications to the suction and discharge valves. The most common cause of mud pump failures is the wears on the valves so there is an urgent need to increase the durability of the inlet and outlet valves. This research will allow us to: - lengthen the functional life of the suction and discharge valves. - develop the mud pump's technical requirements. - enhance the drilling pump's economic effectiveness. Thus, it makes sense to do study on piston mud pump valves in order to improve the technical parameters by making some positive adjustments. A moved forward valve situates which essentially diminishes the affect stretch caused by the effect of a piston pump valve body contrary the valve situates. The valve situate comprises a by and large round and hollow body parcel portion parcel with a fixing surface which is slanted from the external surface of the round and hollow body parcel toward an insides throat of said round and hollow body parcel. The valve body comprises a for the most part disc-shaped parcel and a truncated funnel shaped parcel. An elastomer embed is gotten in a groove within the valve body. The cone shaped parcel of the valve comprises an inclined confront, counting a metal parcel and an elastomeric parcel shaped by the elastomeric embed. Within the valve situate of the present innovation, an annular weight alleviation groove within the round and hollow body parcel of the valve situate permits the inclined confront of the valve situate to flex subsequently calming a noteworthy sum of the affect stack between the restricting confront of the valve gathering. Keywords: suction valve, discharge valve, valve wears, valve seat, poppet valve, piston mud pumps.

Practical tracking results have been reported in the literature for high-order odd-rational-power nonlinear dynamics (a chain of integrators whose power is the ratio of odd integers). Asymptotic tracking remains an open problem for such dynamics. This note gives a positive answer to this problem in the framework of prescribed performance control, without approximation structures (neural networks, fuzzy logic, etc.) being involved in the control design. The unknown system uncertainties are first transformed to unknown but bounded terms using barrier Lyapunov functions, and then these terms are compensated by appropriate adaptation laws. A method is also proposed to extract the control terms in a linear-like fashion during the control design, which overcomes the difficulty that virtual or actual control signals appear in a nonaffine manner. A practical poppet valve system is used to validate the effectiveness of the theoretical findings.

Abstract About nine million barrels of gasoline are consumed daily by automobile engines. Out of this, roughly 2.25 million barrels are effectively used by the engine to generate power, whereas the rest is wasted due to engine inefficiencies. There is a dire need to bring up a more efficient engine, since even an effort for a 1% increase in efficiency would result in savings of almost $6 million daily worldwide. In this study, first, a conventional poppet valve engine configuration for a 70cc engine was analyzed. Then, based on the engine efficiency contributing parameters, a novel Independent Rotary Valve (IRV) engine configuration was proposed. The proposed engine configuration was analyzed for the same 70cc engine. The LOTUS Engine software was used for the thermodynamic investigation of intake valve closing angle for getting maximum values of volumetric efficiency, brake power, and brake torque at different speeds and intake valve closing angles. It has been found that the proposed engine configuration resulted in approximately 1.165% increase in thermal efficiency by a decrease in air-fuel mixture pumping work. In addition, a 13% increase in volumetric efficiency, a 13% increase in brake torque, and an 18% increase in brake power were found, through the use of independent valve actuation. Also, an increase in mechanical efficiency is expected, due to the added simplicity of the proposed IRV as compared to the conventional poppet valve system. This increase has been verified analytically and by numerical modeling performed in ANSYS FLUENT. The proposed IRV engine configuration is thus a more efficient, more powerful, less complicated, more stable, and an environmentally safer engine.

Simulation analysis and experimental research on mechanical properties of water hydraulic ball poppet valve

Poppet valves used in internal combustion engines have a high risk of failure due to significant temperature and pressure. These poppet valves need surface finishing at the nano-scale level to prolong their life during their working use. In the present research, the chosen poppet valve has narrow ridge profiles, which is difficult to nano-finish by conventional processes due to certain limitations. The magnetorheological fluid-based finishing method can be effectively used for this kind of complicated narrow profile. For the magnetorheological fluid-based finishing processing of the poppet valve, a novel magnet fixture and setup is used. For checking the efficiency of this setup, surface characterization and surface roughness for polished and unpolished surfaces are outlined using a field-emission scanning electron microscope, microscope and optical profilometer. The final surface roughness of Sa = 23.1 nm at poppet profiles were obtained. All manufacturing defects like burrs, dents, scratches and pits are almost removed. The study of finishing forces in the magnetorheological fluid-based finishing method is also carried out using magnetostatic fluid–solid interaction, experimental and theoretical analysis. This force analysis supports the development of the material dislodgement model to anticipate material removal rate while finishing. The gap (error = 12.87%) between the experimental and theoretical material removal rate is marginal. It has high accuracy and reliability for specific applications.