SIMULATION OF A WATER CURTAIN APPLICATION TO PROTECT WORKERS FROM THERMAL INJURIES

Problem statement. The problem of evaluating the effectiveness of using the water curtain to reduce the risk of thermal injury to people in a fire is considered. The problem is to determine the temperature fields when supplying water for air cooling. The purpose of the article. Development of a numerical model for calculating the process of propagation of water droplets in the air, their evaporation to reduce the temperature of heated air due to fire. Methodology. For mathematical modeling of the process of propagation of water droplets in air, thermal air pollution, the convective-diffusion equation of mass transfer, the energy equation and the equation describing the motion of an ideal liquid (potential flow model) are used. The potential flow model allows you to quickly determine the field of air flow velocity in areas with a complex geometric shape. Implicit difference splitting schemes are used for numerical integration of the convective-diffusion mass transfer equation and the energy equation. Physical splitting of basic equations is used to construct a difference analogue of modeling equations. The Richardson method and the conditional approximation scheme are used to solve the aerodynamics problem of determining the velocity potential field and the components of the air velocity vector. An engineering method for calculating the process of evaporation of a drop of water based on Sreznevsky's law has been developed. Scientific novelty. An effective numerical model has been developed that allows the method of computational experiment to determine the efficiency of using the water curtain to reduce the level of thermal pollution of atmospheric air due to fire. The numerical model is based on the integration of the fundamental equations of aerodynamics, heat and mass transfer. The model takes into account the most significant physical factors that affect the process under study: the movement of heated air, the movement of water droplets in the air, evaporation of the droplet, and so on. Practical significance. Based on the built model, a computer code has been created that allows you to quickly determine the temperature fields in the air when using a water curtain. The numerical model will be useful when conducting computational experiments for the purpose of scientifically sound choice of the location of the water curtain in case of fire. Conclusions. A computer code has been created that allows a computational experiment to investigate the effectiveness of using a water curtain in a fire. The developed computer program can be implemented on low and medium power computers. The results of a computational experiment are presented.

Hydraulic Conductivity of Rock Masses Surrounding Water Curtain Boreholes for Underground Oil Storage Caverns

The assessment of the groundwater flow rate around the cavern periphery is a critical requirement for the design of underground water-sealed oil storage caverns and commonly made through seepage analysis, where a reasonable estimation of the hydraulic conductivity of the host rock is the key issue. However, it is a challenge to accurately determine the hydraulic conductivity of natural rock masses owing to their heterogeneous and anisotropic nature. The underground storage cavern project has a unique favorable condition in that there is a water curtain system that can provide considerable hydraulic test data for inferring hydraulic parameters; however, no well-established method has ever been proposed to exploit these data for characterizing heterogeneity in hydraulic conductivity. This study presents a new approach to evaluate the spatial variation of hydraulic conductivity using water curtain borehole data. This approach treats the peripheral region of each borehole as a homogenous unit with a particular equivalent permeability coefficient that can be back-calculated from the measured injection flow rate of the borehole using a numerically established empirical formula. Besides, the impact of curtain gallery drainage, occurring in the construction stage, on the seepage field was investigated while the effect of the rock fracture configuration on hydraulic conductivity assessment was examined. The proposed method enables robust and accurate mapping of heterogeneity in the hydraulic conductivity of host rocks and provides a new idea of effectively utilizing hydro-geological test data to derive the hydraulic conductivity of rock masses surrounding water-sealed storage caverns.

Experimental Study of Explosion Mitigation by Deployed Metal Combined with Water Curtain

In this paper, protective barriers made of perforated plates with or without a water cover were investigated. In urban areas, such barriers could be envisaged for the protection of facades. An explosive-driven shock tube, combined with a retroreflective shadowgraph technique, was used to visualize the interaction of a blast wave profile with one or two plates made of expanded metal. Free-field air blast experiments were performed in order to evaluate the solution under real conditions. Configurations with either one or two grids were investigated. The transmitted pressure was measured on a wall placed behind the plate(s). It was observed that the overpressure and the impulse downstream of the plate(s) were reduced and that the mitigation performance increased with the number of plates. Adding a water layer on one grid contributed to enhance its mitigation capacity. In the setup with two plates, the addition of a water cover on the first grid induced only a modest improvement. This blast mitigation solution seems interesting for protection purposes.

Geochemical monitoring of deionized seawater injected underground during construction of an LPG rock cavern in Namikata, Japan, for the safety water curtain system

An underground liquified petroleum gas (LPG) storage facility was constructed between 1998 and 2006 in Namikata, Imabari City, Ehime Prefecture, Japan, to increase domestic LPG stockpiles. The most important issue during construction and operation of this facility is gas leakage prevention. To thwart water leakage, the water curtain system was constructed according to design standards, and a large amount of deionized seawater (seal water) was continuously injected into the rock mass around the cavern to keep the water level constant during both construction and operation. It is possible to distinguish three end member waters (existing groundwater, seawater or fossil seawater, and seal water) using the salinity and isotope (δ18O) difference because seal water injected underground has almost the same δ18O value as seawater. In this study, continuous observation is carried out using the geochemical techniques for flow analysis with a mixing ratio of three end members in the initial construction period (April 2005 to March 2006) of the LPG underground storage facility. It is determined that existing groundwater and seawater originally distributed in this region are partly replaced by seal water in the cavern.