Constructing a Mathematical Model of the Gas-dynamic Separation for Designing Energy-saving Vortex Separators

We developed a mathematical model of the separation process of heterogeneous polydisperse mixtures in the proposed energy saving vortex separators, which is represented by a system of differential equations linking parameters of the process control to the geometric dimensions of device. We showed the possibility to solve a mathematical model based on the grid method for the determination of initial parameters and control parameters of the separation process, as well as for determination of coordinates of components with different shapes, densities, aerodynamic and gas dynamic properties. This will significantly reduce time for calculations of gas-dynamic vortex separators of any mixtures. We proved the reliability of the calculation based on the grid method by comparing it with the results of the experiment. This makes it possible to calculate and design vortex separators without expensive calibrating sieves and energy-intensive vibration equipment. We established the region of a change in the generally accepted coefficients of efficiency and precision of the separation of a flour mixture, which determine the presence of harmful components in a resulting product and the content of high quality components in waste, which should not exceed 2 %.We detected boundary values of the coefficients of efficiency hе=88 % and precision hs=0.9 of mixtures of flour of the highest grade, the first grade, and the second grade, which could be used as the initial data in the design of vortex separators. We proved the possibility to control the separation process by changes in gas-dynamic parameters of a heterogeneous mixture at the inlet to a separator. This will make it possible to change the velocity of redistribution of components of a mixture and to obtain necessary indicators of a resulting product with a predetermined degree of purity. The research results proved the possibility for implementing vortex separators into industrial production. This will significantly reduce the cost of preparation of raw materials in grain processing, coal, and other fields, as well as in the production of dolomite, construction materials, etc. Using the vortex gas-dynamic separators in technological processes would improve production environment and reduce the cost of maintenance and repair, since they operate in a closed cycle and do not contain expensive calibrating sieves and electric drives

Establishment of the Dependence of the Strength Indicator of the Composite Material of Pressure Hoses on the Character of Single Damages

Experimental studies are presented and the dependence of the change in the strength of the material of a pressure head fire hose of type T with an inner diameter of 77 mm in the longitudinal direction is established, taking into account single damages. The work describes the plan of the experiment and carried out a number of field experiments to determine the effect of the length ld and the depth K damage on the strength F of the hose material, that is, obtaining the dependence F=f (ld, K). A mathematical method of experiment planning was used and a plan was drawn up for a complete multivariate experiment of type 2k with an acceptable model accuracy of 5 %. The limits of variation of the factors are set taking into account a priori information, experimental capabilities and on the basis of the results of preliminary search experiments. The dependence in the coded and natural values of the factors is obtained. The reliability of the relationship was checked using the Fisher test, the calculated value of which was 5.98, which confirms the adequacy of the described process with a probability of 95 %. Analyzing experimental studies of the dependence of the change in the strength of the hose material on the length and depth of damage, it can be said that the change in the strength of the hose almost linearly depends on the specified damage parameters. It is found that with increasing damage, the strength of the hose material significantly decreases. When varying the length factor and the greatest depth of damage, K=0.4 mm, the strength of the hose material decreases from 11.67 kN to 8.77 kN, and in percentage terms by 25 %. The results obtained can be used in practical units of emergency rescue teams, when diagnosing hidden damage in pressure head fire hoses in order to prevent their failure in case of fire