Two Wire Sensor for Measuring the Velocity of Non-Isothermal Flows

Changes in the temperature of the medium significantly affect the static characteristics of hot-wire anemometry measuring wires, which causes errors in the results of flow velocity measurements. High temperatures of the medium make it necessary to additionally heat the sensor to even higher temperatures, which may lead to its damage due to wire burnout. The article proposes a solution to the problem of measuring the flow velocity in conditions of non-stationary temperatures with the use of the method of cross-correlation of signals from two-wire resistance thermometers. The main assumptions of the method and its experimental verification were presented.

Analytical solution for unsteady adiabatic and isothermal flows behind the shock wave in a rotational axisymmetric mixture of perfect gas and small solid particles

The approximate analytical solutions are obtained for adiabatic and isothermal flows behind a cylindrical shock wave in a dusty gas. A mixture of perfect gas and micro size small inert solid particles is taken as the dusty gas. The inert solid particles are distributed continuously in the mixture. It is considered that the equilibrium flow conditions are maintained. The flow variables are expanded in power series to obtain the solution of the problem. The analytical solutions are obtained for the first order approximation in both the adiabatic and isothermal cases. Also, the system of ordinary differential equations for second order approximations to the solution is obtained. The influence of an increase in the ratio of the density of the inert solid particles to the initial density of the perfect gas, the rotational parameter and the mass concentration of inert solid particles in the mixture are discussed on the flow variables for first approximation. Our first approximation to the solution corresponds to the Taylor’s solution for the creation of a blast wave by a strong explosion. A comparison is also made between the solutions for isothermal and adiabatic flows. It is investigated that the density and pressure near the line of symmetry in the case of isothermal flow become zero and hence a vacuum is formed at the axis of symmetry when the flow is isothermal. Also, it is found that an increase in the value of rotational parameter or the mass concentration of solid particles in the mixture has a decaying effect on shock wave. The present work may be used to verify the correctness of the solution obtained by self-similarity and numerical methods.

A simulation study of processes for mixing non-isothermal flows under dynamic effects

The processes for mixing of non-isothermal streams essentially define the parameters of the heat-carrier on an input in a core in modes with incomplete structure of the working equipment and, as a consequence, - a heat engineering condition of a core. Besides, the task of researching the temperature pulsations accompanying practically all modes of currents for non-isothermal streams is extremely relevant, as these pulsations lead to additional thermocyclic loadings on elements of the equipment and in many cases define its resource. The paper describes the research of mixing processes for non-isothermal water coolant flows in hydraulic model of ship nuclear power plant. In several experiments, attention was paid to the mixing processes when feeding non-isothermal flows through the circulation loops located opposite of each other. To simulate the effect of external dynamic force in the form of periodic effect on the spatial orientation of the model, the ship was tested on a stand "Swinging platform". These vibrations affected the mixing processes occurring within the model. The main impact they had on the transition time, temperature gradient, vertical component of the velocity projection. In the future, these parameters will be clarified and the influence of other factors on the mixing of non-isothermal flows in the ship's nuclear power plant will be studied in more detail.

A Simple Construction of a Thermodynamically Consistent Mathematical Model for Non-Isothermal Flows of Dilute Compressible Polymeric Fluids

We revisit some classical models for dilute polymeric fluids, and we show that thermodynamically consistent models for non-isothermal flows of these fluids can be derived in a very elementary manner. Our approach is based on the identification of energy storage mechanisms and entropy production mechanisms in the fluid of interest, which, in turn, leads to explicit formulae for the Cauchy stress tensor and for all of the fluxes involved. Having identified these mechanisms and derived the governing equations, we document the potential use of the thermodynamic basis of the model in a rudimentary stability analysis. In particular, we focus on finite amplitude (nonlinear) stability of a stationary spatially homogeneous state in a thermodynamically isolated system.