Seawater Hydraulic System Research Articles

Experimental and theoretical investigation of a miniature simple pressure pulsation attenuator lined with porous polyurethane material

A miniature simple pressure pulsation attenuator (PPA) lined with porous polyurethane material is designed and a theorical model is established for analyzing the pressure pulsation attenuation performance of PPA. The effect of internal structural parameters of PPA and external operating conditions on attenuation performance is investigated theoretically and experimentally. Spectral intensity is used as a new method to evaluate the pressure pulsation attenuation, and other common index such as pressure pulsation rate and frequency spectrum are also compared in detail. The results show that spectral intensity can more accurately reflect the overall effect of pressure pulsation and the attenuation effect at a specific frequency. The present PPA is more suitable for low static pressure and can effectively eliminate low-frequency and high-frequency pressure pulsation. In addition, the diameter and number of pores can affect the pressure pulsation attenuation. Insertion loss of PPA exhibits multiple peaks, which are mainly influenced by liner length and liner material. Furthermore, the flow rate increases as the pulsation frequency increases for the piston pump based on frequency control, which can cause the pulsation attenuation performance to basically remain unchanged. The research offers valuable insights for the design, optimization, and analysis of PPA in seawater hydraulic system.

Research on a Temperature Control Device for Seawater Hydraulic Systems Based on a Natural Gas Hydrate Core Sample Pressure-Retaining and Transfer Device

In the study of natural gas hydrates, the maintenance of the low-temperature and high-pressure state of the core sample under in situ conditions is highly important for cutting, transferring, and subsequent analysis. The pressure maintenance and temperature control device (PMTCD) for natural gas hydrate core samples described in this paper is a subsystem of the pressure-retaining and transfer device. The device consists of a water tank, seawater chillers, a plunger pump and a thermoelectrical refrigeration device. The device cools the seawater to 2 °C, and then pressurizes it to inject it into the sample cylinder. Due to the inevitable heat generated by the pressurization and heat exchange with environment, there is a thermoelectrical refrigeration device to compensate for temperature rise. Finally, the seawater temperature entering the sample cylinder is no higher than 3 °C, effectively preventing the decomposition and deterioration of the natural gas hydrate core in the sample cylinder. In this paper, the temperature increase of the device and its compensation capacity are analyzed in detail on the basis of calculation and simulation. On the basis of testing with the device, it is verified that even at the ambient temperature, the water temperature can still be maintained at 3 °C.

Development of a Multifunctional Abrasion and Friction Test Bench with High Ambient Pressure for Seawater Hydraulics

Seawater hydraulic pump, of which the performances and service life are highly dependent on the structural design and material selection of the friction pairs and sliding bearing, are the power componentof the seawater hydraulic systems. Based on the previous studies, a seawater abrasion and friction test bench with high ambient pressure (≧20MPa) is to be developed for deep-sea (≧2000m) application environments. The technical requirements are presented and comparison analyses have been made between two testing schemes: rotating cylinder-blockscheme and rotating swash-plate scheme. Details are presented on the designs of the three key friction pairs and sliding bearing of the rotating cylinder-block bench. This research provides a test bench for the design of key parts in deep-sea water hydraulic pump/motor and the studies of the related theories (such as the friction and wear theory, lubrication and bearing mechanism).

Design and research on a variable ballast system for deep-sea manned submersibles

Variable ballast systems are necessary for manned submersibles to adjust their buoyancy. In this paper, the design of a variable ballast system for a manned submersible is described. The variable ballast system uses a super high pressure hydraulic seawater system. A super high pressure seawater pump and a deep-sea brushless DC motor are used to pump seawater into or from the variable ballast tank, increasing or decreasing the weight of the manned submersible. A magnetostrictive linear displacement transducer can detect the seawater level in the variable ballast tank. Some seawater valves are used to control pumping direction and control on-off states. The design and testing procedure for the valves is described. Finally, the future development of variable ballast systems and seawater hydraulic systems is projected.

THE SELECTION AND PERFORMANCE OF CERAMIC COMPONENTS IN A SEA-WATER PUMP

Intrinsically, advanced engineering (or technical) ceramics are the optimum material for sea-water hydraulic systems because of their superior mechanical strength, low friction properties, resistance against abrasive, erosive and sliding wear, and corrosion resistance. However, ceramics require a different design philosophy from metallic components, and demand a probabilistic method in the design of structural components together with special attention to the manufacturing and finishing processes. The rationale behind the development of a ceramic axial piston pump for sea-water applications is described below and includes evidence that martensitic stainless steel is intrinsically susceptible to stress corrosion fatigue in such environments.