Abrasive Water Research Articles

Numerical and experimental analysis of hot dry rock fracturing stimulation with high-pressure abrasive liquid nitrogen jet

Abrasive liquid nitrogen (L-nitrogen) jet fracturing is a novel technology, which is expected to be suitable for hot dry rock (HDR) fracturing. In this paper, numerical simulation has been presented to analyze the fluid flow, heat transfer and thermal stresses distribution in HRD fracturing with abrasive L-nitrogen jet. The simulation is carried out with a three-dimensional model in transient state. The low Reynolds number κ-ε model is employed to accurately predict the near wall flow. The heat transfer between L-nitrogen and hot rock on solid-liquid interface is computed by an inverse method of conjugate heat transfer. The thermo-elastic model is used to calculate the thermal stresses distribution in rock. Numerical results indicate that abrasive L-nitrogen jet has a better performance in perforation than abrasive water and supercritical CO2 jet. Great tensile stress distributes in the region near interface, however, its affected depth is limited. This tensile is expected to be favor for fractures generation and growth along perforation direction. Short perforation length can promote the heat transfer on interface. The initial rock temperature has an important influence on values of thermal stresses. Experiments, in which the hot granite specimens with a small hole in center were impacted by L-nitrogen jet, have been conducted to validate the effect of thermal stresses on fracturing. The fractal method is adopt to quantitatively describe the flow and transport capability in rock masses. Experimental results show that numerous thermal cracks were generated on the interface. Rising rock temperature can significantly increase the number and size of thermal cracks and improve the connectivity of fractured rock, which are benefit to fracture initiation during L-nitrogen jet fracturing. The results in this paper would shed light on L-nitrogen jet fracturing for HDR as well as some high-temperature oil reservoirs.

ANALYSIS OF METHODS OF HYDRATING DIAGNOSIS IN FLOWLINES

In this article the main problem of gas industry is shown. This problem if gas hydrate prevention especially in the gas flow lines. The most popular way of gas hydrate prevention is gas hydrate inhibitor supply. As usual it is methanol. To optimize methanol flow rate it is offered to diagnose the conditions of hydrate formation in the flow lines. This problem could be solved by developing the automatic system of diagnosis progressing of hydrate conditions appearance in the flow line and the beginning of this process. Sony well known methods of such system building are shown in this article. According to carried out research we can say that many factors are affected these systems. The correlation between all these factors could not been described analytically. Also there is no enough quantitative information about these factors. So that is why these systems are appropriately built based on fuzzy cognitive map. The cognitive map is made in order to make up for a deficiency in quantitative information and allows to detect the most important (key) factors. These key factors characterize the correlation between the object and environment and relate with them. Command variables in the developed system are formed based on online measured pressure and temperature conditions in the beginning and in the end of the flow line, ambient temperature and water dew point temperature. Also well flow rate, gas composition and its density are important. The selected key factor is theoretical hydrating temperature. The changing of the coefficient of heat transmission and other factors (abrasive particles and water vapors in gas, ground condition and surface relief, snow cover and its condition and others) affects on hydrating temperature. To illustrate the main idea the fuzzy cognitive model is offered in the article. This model corrects the coefficient of heat transmission, and it helps to count theoretical hydrate temperature more accurately. As a consequence it increase the accuracy of methanol supply.

An Investigation in Abrasive Waterjet Cutting of Al6061/SiC/Al2O3 Composite Using Principal Component Based Response Surface Methodology

Abrasive waterjet was found effective in cutting materials like glass, steel and aluminium for various industrial applications. The effect of process parameters on abrasive waterjet cutting (AWJC) of Al6061/SiC/Al2O3 composite was disclosed in the present work. The cutting parameters taken for study were traverse speed, abrasive flow rate, water pressure and stand-off distance. Surface roughness, kerf width and bevel angle of cut were observed as the quality characteristics for various cutting trials. Experiments were designed using Taguchi's L18 orthogonal array and an integrated technique of principal component based response surface methodology (PC-RSM) was disclosed for designing the parameters. Significant improvements were observed in the quality characteristics obtained with optimal parameter setting identified by PC-RSM approach. Abrasive waterjet parameters like water pressure, stand-off distance and the interaction between abrasive flow rate and traverse speed were found to be influential on the quality characteristics.

Effect of modified zirconium oxide nano-fillers addition on some properties of heat cure acrylic denture base material

Background: Polymer nano composite attracted great attention especially because of their unexpected hybrid properties that are synergistically derived from the two components. The aim of this study was to evaluate the effect of addition of modified nano-zirconium oxide on some properties of heat cured acrylic denture base material. Materials and methods: Zirconium oxide nano fillers modified by a silane coupling agent Tri (methoxysilyl) propyl methacrylate before dispersed and sonicated in monomer (MMA)in different percentage 2%,3%and 5%by weight. Three hundreds and twenty specimens were prepared for these studies were divided into five main groups according to the test used. The tests were abrasive wear, water sorption and solubility, porosity, tensile and fatigue strength test. For each test four sub groups (one control and three for different weight percentage of nano-ZrO2). Scanning electron microscope techniques used to analyze the fracture surface of fatigue test and estimate the dispersion and distribution of the nano-ZrO2 particles. Results: Highly significant increase in abrasive wear resistance with 3wt% and 5wt% of nano fillers with all groups of denture cleansers. highly significant decrease in water sorption and solubility. Significant decrease in porosity in 3wt% and 5wt%. Highly significant increase in both tensile and fatigue strength in all groups but slightly decreased in 5wt% as compared with 3wt% but still high significant as compared with control group. Conclusion: incorporating the modified nano-ZrO2 into acrylic resin results in improvement in abrasive wear resistance, tensile and fatigue strength in addition decrease in water sorption, solubility and porosity of heat cure denture base resin.

Applications of Ultra High-Pressure Powder-Abrasive Waterjet

The paper describes the technique developed for applying garnet powder abrasive ultra-high pressure water jet advanced technology (AWJ) to build accurate models of artistic objects. The objects to be modeled have been selected through a cooperative initiative between the University of Sao Paulo and entities of the private sector. The first application was the reproduction of the artistic floor of marble at the St. Mark's Basilica, Venice, Italy. The other application was the production of official trophies for a technical awards ceremony for a national symposium that took place in Brazil. The trophies were made in stainless steel, whilst the floor reproduction was made in ceramic tiles. The floor was reproduced from high-definition photography of the original floor. The design concept and the blueprints of the trophies were originally conceived by the symposium organizers. Both models have been built using OMAX® CAD/CAM Software, which controls an AWJ unit installed at the University of São Paulo, where the procedures for building both models have been developed and executed with high success.