Influence of Wheel Blunting on the Machining Precision in CNC Plunge Grinding: Digital Twin Analysis

Russian Engineering Research - The machining precision in grinding a flexible shaft by sharp and blunt wheels is compared for a CNC system with a specified cycle of radial supply velocities. To...     

Influence of Instrument Position in Active Monitoring on the Accuracy and Productivity of CNC Plunge Grinding

Russian Engineering Research - In active monitoring, the position of the instrument may influence the accuracy and productivity of machining. This influence is considered in the present work for...     

Influence of Variable Machining Conditions on the Precision in CNC Plunge Grinding: Predictive Analysis by a Digital Twin

Russian Engineering Research - A system for predicting the machining error for a batch of parts in CNC wheel grinding is described; the system takes the influence of technological variables into...     

The influence of combustion efficiency on the characteristics of ramjets

Methods for determining the combustion efficiency, thermodynamics parameters of propellants, and characteristics of ramjets are analyzed. Energetic and multizone models taking into account various physical processes of incomplete combustion are considered. An approach based on comparison of the combustion efficiency evaluated by different models is developed, and recommendations on their application are given. The results and mathematical models presented can be used in numerical computational and experimental studies of the working processes in ramjets.     

Pseudotransient Continuation-Based Steady State Solver: Extension to Zero Flow Rates

This paper presents and discusses an extension of the pseudotransient continuation-based steady state solver for hydraulic networks proposed previously to the case of zero flow rates. The original solver, which reduces the solution of the governing nonlinear algebraic equations to the numerical integration of an initial-value problem, has problems in situations in which the head derivative of the flow rate tends to infinity, as is the case with zero flow rates. The extension is on the basis of the use of a model headloss-flow relationship that coincides with the true one at zero and has a finite head derivative at that point. This modified steady state solver is free from some convergence problems that occur in Newton-Raphson method-based solvers when analyzing a pipe network with control devices. The paper includes the results of the numerical analysis of test networks, which demonstrate the convergence of the modified steady state solver for cases in which existing steady state solvers have troubles.     

Optimizing the flame aerodynamics and the design of tangentially arranged burners in a TGMP-314 boiler

Technical solutions for optimizing the flame aerodynamics and the design of tangentially arranged burners in a TGMP-314 boiler are proposed. The implementation of these solutions will make it possible to achieve more reliable operation of the boiler during fuel oil combustion, smaller amount of NO _x emissions during the combustion of gas and fuel oil, and a somewhat lower air excess factor in the furnace.     

Acceleration and heating of powder particle by gas detonation products in channels with a conical passage

The results of numerical modeling and experimental realization of the impact of a chemically reacting gas flow on powder particles during profiling (diameter increase while maintaining volume) of the barrel combustion chamber of a unit for detonation spraying are given. The passage from the combustion chamber into the barrel muzzle is made using connecting taper sleeves with a small narrowing angle. It is shown that such profiling can significantly reduce the barrel size without compromising the technological capabilities of the detonation unit.     

The influence that a zirconium additive has on the strength and electrical resistance of cold-rolled aluminum sheets

The influence that a Zr additive (0.3–0.6 wt %) and annealing modes have on the electrical resistance and mechanical properties of cold-rolled sheets obtained from cast ingots on the basis of technical grade A7E aluminum is investigated. It is shown that all zirconium-doped alloys retain deformation strengthening after 1-h annealing at 300°C, in contrast to undoped aluminum. In this case, as the Zr concentration increases, the strength properties improve, which may be associated with the summation of two effects: deformation and dispersion. It is established that, as the Zr content increases, the resistance of cold-rolled sheets substantially increases; however, after annealing, this characteristic is first of all determined by the zirconium concentration in the aluminum-based solid solution and depends on the parameters of heat treatment.