Experimental and Numerical Study on the Plume Rising in Stairwell of Buildings

In recent years, it has been observed that when a fire occurs in a multi-use facility, a toxic fire smoke rapidly rises through the vertical shaft and spreads due to the chimney effect and hot buoyancy. Generally, the fire smoke spreads rapidly through a number of evacuation passages installed for safe evacuation, which adversely affects an emergency situation. Due to the lack of this knowledge among the occupants, the majority of the occupants are evacuated using the stairwells, getting suffocated by poisonous smoke and suffering serious injuries. The present study considered the fire smoke spreading vertically through the stairwell. For this purpose, the power of the heat source and the area of the ventilation windows connected to the stairwell were modified, and the movement and diffusion of the hot plume rising vertically in the stairwell were observed. For the experiment, a 1/20 scaled-down stairwell model was employed, and the temperature ‘T’ and the vertical velocity ‘w’ of the hot plume rising inside the stairwell were measured using a 60 W-180 W heat source power. Numerical analysis was performed using FDS under similar conditions, and the results were compared with the experimental results.

Model for calculation of anchor parameters fixings for vertical exploration works

It is known that effective rock hardening, as opposed to the action of tensile stresses, can be performed using anchors of various designs, depending on the specific mining and geological conditions. At the same time, there are very few publications on the calculation of roof bolting parameters for vertical shafts of different cross-sections. Therefore, in this work, a method has been developed for calculating such a support for vertical shaft shafts. Calculations were made only for the working wall, which is more dangerous in terms of fallout. Anchors are considered to work in tension when this wall is attached. For the opposite wall, such calculations are not required. Considering that here the anchors are being introduced in a direction perpendicular to the direction of bedding of rocks and they will work on a cut. In this case, the shear strength of metal and reinforced concrete anchors is 4-5 times higher than their tensile strength. The calculation method consists of methods for determining the lengths of the anchor and its locking part. In this case, the length of that part of the anchor is taken into account, which is enclosed between the base of the cone of influence of the anchor and the border of the zone of possible fallouts. The resulting formula for the length of the joint part of the anchor strongly differs from the previously known similar formulas by other authors, taking into account the effect of rock pressure, which varies with depth. Its structure contains the factor of the bedding angle with respect to the horizon and the coefficient of friction of the rock about the rock, leading to a decrease in the length of the anchor lock part. In addition, the volume of destroyed rocks in the zone of influence of the anchor is taken as the volume of the cylinder, which corresponds to the actual operating conditions of the anchor.

Sloshing of Fluid Between Rotating Inner Vertical Shaft and Stationary Outer Casing

Unsteady behaviors of free surface around a rotating vertical shaft in cylindrical stationary casing were investigated. Experiments were carried out with various rotating frequency of the shaft at two initial water levels. An axi-symmetrical free surface oscillation took place when the rotational speed of the shaft became larger than a certain value. The frequency of the free surface oscillation decreased as the rotating frequency increased. A theoretical model was developed, and the mechanisms of the free surface oscillation were clarified. The oscillation was found to be a sloshing mode excited by the change of fluid angular velocity, caused by the change of wetted areas on the inner rotating shaft and outer stationary casing, associated with the change in free surface height.

Wear Law and Parameter Optimization Study on the Split Cone of a Vertical Shaft Impact Crusher

During the sand-making process, the wear of the split cone will affect the dynamic balance of the rotor and the sand-making effect of the crusher. This paper focuses on experiments and simulations with the rotor of a vertical shaft impact crusher. A wear model for predicting the wear value of the split cone is established and its effectiveness is verified. The orthogonal test of L 16 4 4 is designed. By using the range analysis method, the influence of the rotor speed, the feed height, the installation angle, and the number of the guide plate on the wear resistance of the split cone are studied. By using the multiple linear regression analysis method, the optimal parameter combination of each factor is obtained. The results of this paper show that the wear resistance of the split cone is the best when the installation angle of the guide plate is 40°, the installation number of the guide plate is 3, the rotor speed is 2800 r/min, and the feed height is 40 mm.