Determination of the influence of a clearance between the case and blade ends of the semi-open impeller on the centrifugal compressor stage characteristics

The influence of the clearance between the case and blade ends of the semi-open impeller on the centrifugal stage characteristics is considered using the experimental data and numerical calculation results.     

Influence of geometry and operating conditions of a centrifugal compressor stage on the radial gas force

The influence of geometry and operating conditions of the centrifugal compressor stage on the radial gas force is determined on the basis of the theoretical method and calculation program using experimental boundary conditions.     

Application of high-order accurate methods to solve the computational gas dynamics and aeroacoustics problems

The application of the low dissipative high-order accurate scheme for numerical solution of the Euler and Navier-Stokes equations in the two-dimensional statement is considered. The scheme of calculating space derivatives is the seven-point central-difference approximation of the fourth order with the coefficients optimized to reduce the dispersion errors. The optimized six-step Runge-Kutta method is used for evaluating the time derivatives. By means of filtration, spurious pulsations are suppressed and shocks are processed. The results of verifying the calculation scheme realized on the stationary problem of flow around the model turbine blades are presented.     

Calculation of setup variables for the process of bending and rolling thin-walled components using the finite difference method

A mathematical model of the process of bending and rolling the thin-walled components is presented taking into account the geometrical nonlinearity. Also presented is the technique for calculating the setup variables of bending equipment, which is based on reduction of the initial differential boundary-value problem to the discrete one with the use of the finite difference method.     

Vibrations of an elastic guide beam with a missile moving along it

Transverse nonstationary vibrations of a guide beam having the initial flexure are considered. An absolutely rigid missile moves under the propulsive force along this guide beam on two sliding supports. The beam displacements introduced by its vibrations are presented as an expansion with respect to the given functions according to the Ritz method. The equations of nonstationary vibration of the beam with the missile moving along it are obtained in the generalized coordinates, the expansion coefficients being chosen as them. The example is presented. Also studied is the effect of different beam and missile parameters on the beam displacement and transverse and angular velocity of the missile.     

Thermal stresses in a multilayer hollow cylinder under thermal shock on its external surface

An exact analytical solution of the thermoelasticity problem is presented for a multilayer shallow cylinder with physical properties of the medium that are constant in the limits of each layer. The effect of thermal shock of different intensity as well as the penetration depth of thermal disturbance on the distribution of radial and circumferential thermal stresses has been studied as applied to the one- and two-layer cylinder. It has been shown that the circumferential compressive stresses appear on the external surface of the cylinder under thermal shock while the tensile stresses appear on the internal surface.     

Flow between finite and infinite disks with consideration of surface mobility

A problem of modeling the incompressible viscous flow between two disks taking into account the rotation of one of them is considered. We study the effect of the disk angular velocity (flow regimes) in the interdisk spacing, finiteness (infiniteness) of disk radiuses, calculation region configuration as well as distances between disks on the flow characteristics, particularly, on the resistance moment coefficient. Numerical simulation is performed with the aid of Maple and ANSYS Fluent software.     

Water feed influence on nitric oxide emission under oxidation of near-stoichiometric air-methane mixtures

We considered the influence of temperature on the nitric oxide emission under combustion of the near-stoichiometric mixtures with and without water feed. We revealed the advantage of the method of fuel-water-air mixture combustion over that of the leaned mixture combustion.     

Calculations of shock wave energy parameters in the presence of high-voltage electrical discharge in water for the transition region

A technique for calculating the energy parameters of shock waves at electrical discharge in water is presented for the transition region of discharge channel expansion using as the base the predetermined characteristics of discharge circuit. The technique is based on the solution of energy transport equation that is similar in form to that of radiative transfer. The validity of the presented approach was experimentally verified.