Ice breaking by a high-speed water jet impact

Ice breaking has become one of the main problems faced by ships and other equipment operating in an ice-covered water region. New methods are always being pursued and studied to improve ice-breaking capabilities and efficiencies. Based on the strong damage capability, a high-speed water jet impact is proposed to be used to break an ice plate in contact with water. A series of experiments of water jet impacting ice were performed in a transparent water tank, where the water jets at tens of metres per second were generated by a home-made device and circular ice plates of various thicknesses and scales were produced in a cold room. The entire evolution of the water jet and ice was recorded by two high-speed cameras from the top and front views simultaneously. The focus was the responses of the ice plate, such as crack development and breakup, under the high-speed water jet loads, which involved compressible pressure ${P_1}$ and incompressible pressure ${P_2}$ . According to the main cause and crack development sequence, it was found that the damage of the ice could be roughly divided into five patterns. On this basis, the effects of water jet strength, ice thickness, ice plate size and boundary conditions were also investigated. Experiments validated the ice-breaking capability of the high-speed water jet, which could be a new auxiliary ice-breaking method in the future.

An experimental and simulation study of the flow pattern characteristics of water jet impingements in boreholes

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

A method to optimize the length of flexible hose of the radial jet drilling technology

Radial jet drilling (RJD) technology has been applied to enhance the recovery of difficult-to-produce reserves by multiple horizontal micro-holes. The micro-hole length drilled by high-pressure water jets is of vital importance for the oil and gas recovery effect and is usually tens of meters long for applications in maturing oil fields in China. The water jets are generated by multiple orifices nozzle generally. Many studies focused on improving the self-propelled force generated by water jets to increase the micro-hole length. However, there are few researches on improving the micro-hole extension capacity in terms of optimizing the flexible hose that acts as the drill pipe in conventional drilling technology. This paper firstly studied the relationship between the flexible hose length and the micro-hole extension limit according to the analytical model to calculate the micro-hole extension limit. Then, the method to optimize the flexible hose length and the flow rate was developed aiming to obtain maximum micro-hole extension limit. The results show that the micro-hole extension limit decreases logarithmically with the increase in the flexible hose length under the condition that the takes the maximum value. The optimization model is applied by a field case and is proved to be effective to increase the micro-hole extension limit. This study is significant to improve the micro-hole extension capacity. Moreover, it provides a reference for the design of the hydraulics and selection of flexible hose for the RJD.

RECONSTRUCTION OF THE WATER SUPPLY AND SEWERAGE SYSTEMS OF A CAST-IRON FOUNTAIN IN PAVLOVSK

Introduction: The restoration of old fountains is essential to the cultural life of society since it preserves the architectural spirit of the past and conveys the historical heritage to the present day. Besides, fountains create a favorable atmosphere in summer, humidifying the air. In the course of the study, we developed an approach to the restoration of the engineering systems and the technology of operation of an old fountain in St. Petersburg. Methods: We performed a detailed survey of the cast-iron fountain body and the pits next to it to discover the catchment basin of the fountain and establish its dimensions, assess the operation of similar fountains, analyze historical documents (old photos), and design engineering systems. Results and discussion: As a result of the study, the dimensions of the fountain and the catchment basin as well as the diameters of the orifices were obtained. The trajectories of the water jets and the scheme of the fountain’s operation were determined. Besides, we performed a hydraulic analysis of the systems and selected the necessary equipment. In this paper, we also present the scheme of the fountain’s operation in the following modes: filling with water, normal operation, and shut-down for winter.

Laboratory-Scale Investigation of the Utilisation of Multiple Flat-Fan Nozzles in Descaling Petroleum Production Tubing

Despite the recent wide embrace of mechanical descaling approaches for cleaning scales in petroleum production tubings and similar conduits with the use of high-pressure (HP) water jets, the process is still associated with downhole backpressure and well integrity challenges. While the introduction of sterling beads to replace sand particles in the water recorded high successes in maintaining well completion integrity after scale removal in some recent applications of this technique, it is, unfortunately, still not without questions of environmental degradation. Furthermore, the single nozzle, solids-free, aerated jetting descaling technique – recently published widely – is categorized with low scale surface area of contact, low descaling efficiency and subsequent high descaling rig time. The modifications to mechanical descaling techniques proposed in this work involve the use of three high-pressure flat fan nozzles of varying nozzles arrangements, standoff distances and injection pressures to remove soft scale deposits in oil and gas production tubings and similar circular conduits. This experiment provides further insights into the removal of paraffin scales of various shapes at different descaling conditions of injection pressures, stand-off distances and nozzle arrangements with the use of freshwater. The results obtained from this study also show consistency with findings from earlier works on the same subject.