Improvement of Mixing Processes in Diesel Engines

The object of research is gas-dynamic vortex processes in heterogeneous polydisperse flows. One of the most problematic issues in engine building is the completeness of combustion and the rate of fuel burnout in the given coordinates on the allotted hourly interval in the combustion chamber. These indicators, in turn, determine stringent requirements for used fuels in terms of thermophysical parameters that affect sawing, evaporation and mixing with an oxidizer. In the course of the study, methods of mathematical modeling were used based on the theory of similarity. Methods have been developed for preparing a combustible mixture for detonation-free combustion of a cheap alternative fuel. A method for assessing the quality of spraying low cetane fuel is proposed. A mathematical model is obtained for calculating the change in the parameters of the quality of atomization and the differential characteristics of fuel injection. This is necessary for theoretical studies of gas-dynamic processes in additional power systems for diesel engines in an unsteady three-dimensional flow with variable parameters of a polydisperse flow of a combustible mixture. It has been proven that with a decrease in the camshaft rotational speed, the injection speed will be insufficient to achieve the required spray quality due to a decrease in the speed. This made it possible to redesign the additional system using a separate dual fuel supply. Research samples of an additional power supply system for the ЯМЗ–24 ОН diesel engine (Yaroslavl Motor Plant, Russia) have been developed. Comparative tests of the engine operation on stable gas condensate with the main fuel equipment and an additional system have been carried out. Oscillograms of the tests were obtained and analyzed. The research results provided the basis for the use of low cetane cheap gas condensate in diesel engines. This will improve the economic, power and environmental performance of the engines. Compared to standard cetane fuels, the price of fuel will decrease by 40 %, engine power will increase by 20 %, and the environmental performance of exhaust gases will decrease by 10–30 %

Analysis of the Influence of Aerodynamic Qualities of the Components of Mixtures on Separation in Power-saving Vortex Vehicles

The object of research is gas-dynamic vortex processes in heterogeneous polydisperse flows. One of the most problematic issues is the determination of the aerodynamic characteristics of the components of a heterogeneous polydisperse medium, which are necessary to create a mathematical model of the separation process. The study used methods of mathematical modeling based on the theory of similarity. A technique has been developed for assessing the aerodynamic parameters of mixture components, on the basis of which a number of aerodynamic similarities have been compiled. The coefficients of lift, aerodynamic drag, lateral force, longitudinal, transverse and rotational moments of the components of the grain mixture are obtained. This is necessary for theoretical studies of gas-dynamic processes in vortex separators in unsteady three-dimensional flow with variable flow density, concentration and flow rate of the separated mixture components and the carried fractions. The Reynolds vibration criterion is obtained, based on which the trajectories and energy of the vortex motion of individual components and the separation degree of heterogeneous mixtures are determined. This allows to improve the mathematical model of the distribution process of heterogeneous polydisperse mixtures in the proposed energy-saving vortex separators. The obtained results provide the basis for improving the general theory of heterogeneous vortex flows by introducing an external disturbance criterion that takes into account the drag of the vortex force field and the amplitude-frequency energy level. Thanks to this, it is possible to evaluate the influence of any argument in the desired function. The research results make it possible to automate the analysis of process characteristics and compare them by parameters with experimental data. And also to evaluate the correspondence of dynamic, kinematic and gas-dynamic functions calculated from the given geometric parameters of the vortex devices with the functions obtained from the averaged values. These data makes it possible to work out a range of variations in the parameters of the geometric design of vortex apparatuses by zones, parameters at the inlet, outlet, and degrees of separation, minimize the number of manufactured laboratory and semi-industrial vortex apparatuses, and unify a number of units. Compared with similar known separators, vortex apparatuses are proposed that reduce the cost of preparing raw materials in the grain mill area by a factor of tens due to the elimination of moving working parts, assemblies and screens

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