Transactions of Academenergo 2010 №2

THE SOLUTION OF THE PARABOLIC EQUATION OF HEAT TRANSFER IN CONVERGENT AND DIVERGENT CHANNELS WITH SMALL REYNOLDS NUMBERS USING FOURIER METHOD
E.K. Vachagina, G.R Galiullina, G.R Khalitova

e-mail: evachagina@mail.ru

Keywords: parabolic equation, Fourier method, convergent and divergent channels, Newtonian liquid, convection heat exchange, rheological characteristics, mathematical model, numerical iterative method, variable separation method.

Divergent and convergent channels are widely used as convective heat exchange intensifiers in power industry. In most cases it is impossible to obtain an analytic solution of a heat exchange problems. Usually they use various numerical methods. The analytical solution of such problem with some additional assumptions is suggested.

N.N. Kovalnogov , E.V. Fokeeva

e-mail: nnk@ulstu.ru , katf0k@mail.ru

Keywords: gas-dynamical temperature stratification, a disperse working body, a supersonic stream, ribbed working surface, optimization

The opportunity of efficiency increase of process of gas-dynamical temperature stratification in a disperse stream is analyzed due to longitudinal edges on a surface of heat exchange in a path of subsonic current and optimization of their sizes. As a result of theoretical research it is established that due to use of a disperse working body and optimization of parameters the increase in a transmitted thermal stream in a pipe of temperature stratification in 3.77 times is reached. For the account of working surface ribbing and optimization of the sizes of edges the additional increase in a transmitted thermal stream in 1.9 times is provided.

R.A. Tyryshkin, A.N. Sabirzyanov, V.A. Fafurin, V.V. Fefelov, V.B. Yavkin

e-mail: office@ooostp.ru , sabirzan@sd.kstu-kai.ru

Keywords: velocity profile, developed turbulent flow, smooth tube, RANS model of turbulence, correcting factor, ultrasonic flowmeter.

On the basis of numerical solution of equations for steady state incompressible turbulent flow in smooth round tube velocity profile and correcting factor for ultrasonic flowmeter was obtained. Numerical results of data received from Nikuradze’s experiments have been compared. It is shown that RNG k-? model of turbulence with enhanced wall treatment allows finding velocity profile and metrological parameters of ultrasonic flow meters adequately. Range of applicability of this model under Reynolds number to solve this problem has been analyzed. Numerical results of stabilization length determination for velocity profile have been compared with semi-empirical equations.

A.G. Laptev, R.N. Akhmetov

e-mail: drag777@inbox.ru

Keywords: heat-transfer factor, interface model, a rough plate, factor of resistance of a plate, dynamic speed, a thickness of a turbulent interface.

The paper represents the calculation of heat transfer factors under turbulent movement of a single-phase stream on smooth and rough plates, results of which were received on the basis of the known models of Prandtl’s, Karman’s, Landau and Levitch’s boundary layer theory. The comparative analysis based on known experimental data on heat transfer has been done.

V.V. Sergeev, A.S. Aleshina

e-mail: ascent2@yandex.ru

Keywords: biomass, generating gas, diesel power station, power effective technologies.

We consider the scheme of gasifier power plant. The presented gasifiering set allows utilizing of plant biomass by gasification technology. We suggest the variant with the reconstruction of typical diesel generators to using power gas with low calorific value. The specific features of the plant and its technical characteristics are given. Estimation of economic efficiency of gasifier diesel power plant was provided. The characteristics of the fuel are analyzed. Ways to improve the effectiveness of the proposed power plant are identified.

N.D. Chichirova, A.A. Chichirov, A.I. Lyapin, D.Yu. Matveev

e-mail: pinpin3@yandex.ru

Keywords: system of thermal power plant is the heating network, material balance, chemical analyzers, monitoring of the coolant system of automated control.

The mathematical modeling of physical and chemical processes in thermal power plants system – the closed thermal network, has been carried out. The differential equations systems are worked out for the description of the system material balance following the model of the ideal mixture flowing reactor. Computer programs which have been brought together in a uniform set of applied programs are developed. The initial data for calculation within the applied programs are the heat-carrier quality indicators which are defined at typical points of the system’s chemical control. The application of electrochemical sensors (the analyzers of ionic structure) for the automated system organization of the immediate physical and chemical control (monitoring) of the system’s heat-carrier state is offered. The description of the technological scheme, the devices availability and operation algorithm of the heat-carrier chemical control system are presented.

B.V. Ilchenko, R.A. Sitdikov

e-mail: ilchenkoboris@pochta.ru

Keywords: steam turbine, repair technology, finite element method, stress strain state, residual life.

The paper presents a new disc repair technology of steam turbines operating in the zone of phase transition. The method consists in a sample of the layer of damaged material from the mounting hole of the connection with the blade disc and its replacing with bush. Using the finite element method a numerical calculation of stress strain state of five variants of the repaired holes has been done. The nonlinear behavior of structural material and contact interaction between the disk, rivets, bushes and blades were taken into account. Based on the results of numerical studies the residual life of the repaired disk was evaluated. According to the strength and lifetime parameters optimum variants of constructive changes of the geometry are defined.

D.V. Toporov, B.V. Ilchenko, R.R. Yarullin

e-mail: denistop5@mail.ru

Keywords: static strength, low cyclic fatigue, stress concentration factor, turbine disk, elastic-plastic loop

Experimental studies of both the static and the low cyclic characteristics on smooth and notched specimens cut out from a power steam turbine disk are performed. The kinetic of the elastic-plastic hysteresis loops as a function of number of accumulated cycles are stated. It is found discrepancies for static and low cyclic elastic-plastic characteristics for different zones of the turbine disk.

V.N.Shlyannikov, A.V. Tumanov

e-mail: shlyannikov@mail.ru , tymanoff@rambler.ru

Keywords: crack-tip singularity parameters, surface crack, semi-elliptical crack, inclined crack, biaxial loading

Two types of surface semi-elliptical cracks under biaxial mixed-mode loading are considered in this work. It is a semi-circular and semi-elliptical crack with aspect ratio a/c=0.5. Numerical method of singular parameters determination is suggested accounting for first term of asymptotic expansion. Crack-tip singularity parameters behavior for particular cases of the equi-biaxial tension and the equi-biaxial tension-compression are presented.

V.S.Galustov

e-mail: politehnika_yar@mail.ru

Keywords: water turn, water-cooling tower, power efficiency

The work presents the results of the analysis of various schemes of turnaround use of cooling water at industrial enterprises on the basis of the offered concept of ideal turnaround system. It allowed to reveal typical errors and delusions. Modern cooling devices are analyzed with a view to their efficiency and profitability. Alternate solutions on the basis of the maximum target and power efficiency on construction of optimum water turnaround systems, both for extended and atypical cases are offered.