Search

This work is devoted to the nonlinear buckling of the hemispherical shells subjected to extremely high external pressure. The shells are made of maraging steel with yield strength of 2100 MPa. The experiment on a tentatively devised laboratory-scale hemispherical shell is conducted in high pressure chamber, after preciously fabricated, optically and ultrasonically measured. Numerical predictions are carried out and proved to have a good agreement with experimental results. The laboratory-scale hemispherical shell can borne the pressure as high as about 139 MPa and demonstrates an unstable post-buckling character and a local dimple post-buckling mode near the base. Based on the study, a segmented hemispherical configuration is conceived and evaluated numerically, which can provide a reference for the deep-sea pressure hull design made of maraging steel.

There are several installations with shock tubes in the world, in which a shock wave in air propagates at a speed close to the second cosmic one. Such velocities are achieved by supplying of high energy (~ 1 MJ) to the pushing gas in the high-pressure chamber.

Spray cross-impingement in a high-pressure chamber (10–30 atm) was studied experimentally, the results being compared to the spray opposed-impingement. The comparison was subsequently extended to the spray combustion in a model opposed-piston compression ignition engine. To account for the ambient pressure effects in collision outcomes, a recently proposed pressure-dependent droplet collision model was implemented in the KIVA-3V computer program for simulating the experiments. Compared with the widely used Estrade et al.’s and O’Rourke’s models, the pressure-dependent model produces satisfactory predictions to spray characteristics. The uncertainty of the kinetic energy recovery coefficient, which affects the post-collision characteristics of bouncing droplets, was found to cause insignificant difference in model predictions. In the high-pressure chamber, droplet collisions in cross-impingement occur earlier than those in the opposed-impingement and result in more coalescence, consequently producing larger droplet sizes. With increasing the ambient pressure, the increasing tendency of droplet bouncing diminishes the difference of these two spray impingements. In the model OPCI, the presence of strong swirling flow deflects sprays from impingement and therefore the opposed-impingement shows slightly better combustion performance by producing more spatially uniform droplet distribution. However, the spray cross-impingement enhances droplet collision hence promotes atomization in the absence of swirling flow.

In this study, carbon fiber was exposed to a pressure of 7 MPa for 24 h in high pressure chamber. The tensile test for carbon fiber was conducted to estimate the effect on the high pressure hydrogen in the atmosphere. To determine the tensile strength and Weibull modulus, approximately thirty carbon fiber samples were measured in all cases, and carbon fiber exposed to high pressure argon was evaluated to verify only the effect of hydrogen. Additionally, carbon fiber samples were annealed at 1950 °C for 1 h for a comparison with normal carbon fiber and then tested under identical conditions. The results showed that the tensile strength scatter of normal carbon fiber exposed to hydrogen was relatively wider and the Weibull modulus was decreased. Moreover, the tensile strength of the annealed carbon fiber exposed to hydrogen was increased, and these samples indicated a complex Weibull modulus because the hydrogen stored in the carbon fiber influenced the mechanical characteristic.

The titanium alloy high-pressure chamber studied in this paper serves as a key component of the manipulator-held sampler, which has an ability of in-situ pressure-retaining and used for deep-sea sediment in manned submersibles. Finite element analysis (FEA) had been used to analyze the burst of the high-pressure chamber with original structure under simulated deep-sea condition. Numerical results showed that the burst was due to stress concentration on the top rounded surface of the lower section of pressure chamber, so the structure of high-pressure chamber was further designed to eliminate this stress concentration. After improvement, the maximum principal stress of the concentration point on modified structure was 396.672 MPa about two times smaller than that on the original structure (809.282 MPa). Moreover, an experimental test was carried out to verify the modified structure. The experiment results showed that the in-situ pressure-retaining ability of modified high-pressure chamber could achieve 93% under an ambient pressure of 60 MPa, and the ability was 86.7% when exposed to 71.5 MPa.

Developed high-pressure chamber with a 50 % increase in reaction volume consisting of an oxide container (ZrO2 – Y2O3 ) and locking pads allow to carry out an experiment for high-pressure type “splitsphere-300” at pressures up to 7.0 GPa and temperatures up to 1600 °C and to grow diamond single crystals up to 2 carats, as well as to receive nanostructured diamond compacts and double-layer diamond carbide inserts (DCI). It was established experimentally that for uniform fi lling of all the cavities between the carbide punches and even their optimal loading a container with a porosity of 20 – 25 %.

The construction and operating principle of a pendulum magnetometer for measuring the magnetic susceptibility of solids under high gas pressures are described. This device is distinctive in having the pendulum mounted directly in the high pressure chamber. Experimental plots of the susceptibility of the compound V4S9Br4 as a function of pressure up to 2 kbar at temperatures of 60–300 K are presented as an example of the use of the magnetometer.

The effect of high pressures (up to 45 GPa) and frequencies of the alternating-current (ac) electric field (10 Hz–10 MHz) on the electrical properties of multicomponent copper and silver chalcogenides has been studied. The behavior of the direct-current (dc) electrical resistivity of the samples has been analyzed under uniaxial pressure along the measuring electric field.

A 24-year-patient with Double-Chambered Right Ventricle (DCRV) got pregnant and echocardiography revealed the pressure of high pressure chamber was equal to the left ventricle and she was told the risk for the index pregnancy and had intracaradiac repair after termination of the pregnancy. Another 23 year patient with Ross procedure was told there was a severe pulmonary stenosis of the composite graft and was recommended re conduit replacement after termination. These two patients had not enough cardiac examination and did not understand well their own cardiac performance. For patients with congenital heart diseases, both education of their cardiac status and preconceptional counseling is necessary when they reach childbearing age depending on the patients’ age and development.

In order to reduce the leakage of the axial clearance, the sealing strip is mounted at the top of the scroll tooth. For achieving the axial displacement compensation seal, it is put forward to open a hole that it is in one side of the high pressure chamber at the bottom of sealing groove. The high pressure chamber gas is introduced into the bottom of the seal. It can form a pressure difference. The article begins with the design of sealing groove structure. The stress analysis was carried out on the sealing strip, and sealing strip was established displacement calculation model of change. Secondly, through the simulation experiment, the friction and wear properties of several kinds of seal materials are compared and analysed. To select PEEK as sealing strip material is the most appropriate. Finally, taking typical parameters of involute scroll compressor as an example, the compressive performance of scroll teeth with sealed structure and non-sealed structure is simulated. The results show that the sealing displacement and axial clearance are basically the same under the two schemes. The sealing scheme is proved to be feasible. This lays the foundation for the further study of the axial seal of the variable section scroll compressor.

A high-pressure chamber with an enlarged by 50% reaction volume has been developed. It consists of an oxide container (ZrO2–Y2O3) and sealing pads. By this means, experiments may be conducted at pressures up to 7.0 GPa and temperatures up to 1600°C on a 300 split-sphere high-pressure system. Diamond single crystals (up to 2 karats) may be grown in this system, and nanostructured diamond components and double-layer diamond–hard-alloy plates may be produced. Experiments show that containers with 20–25% porosity are optimal for uniform filling of the whole chamber between the hard-alloy punches and uniform loading of the punches.