火烧油层驱油特征的参数敏感性分析

在火烧油层驱油机理的基础上，依据油气层渗流理论，燃烧理论，建立了火烧油层驱油数学模型。用数值解法对干式和湿式两种燃烧进行了比较，得出：湿式燃烧比干式燃烧的驱油效果好。针对湿式燃烧的特点，对火烧油层驱油过程中的参数进行了敏感性分析，取得了有关结论即1）蒸汽带驱油是火烧油层过程中的一个重要机理；2）随着湿式燃烧水气比的增加，发生氧化反应的区域长度扩大，蒸汽带的温度下降，对流前缘速度增加，加速了热对流的传导，驱油效率增大；3）在湿式燃烧过程中，随着氧气利用率的降低，发生氧化反应的区域长度扩大，蒸汽带的温度下降，燃烧1立方米油砂所需空气量增加，燃烧前缘速度减少，驱油效率几乎不变；4）在湿式燃烧过程中，随着注入空气量的增加，发生氧化反应的区域长度扩大，蒸汽带的温度升高，燃烧前缘速度增加，对流前缘速度增加，加速了热对流的传导，驱油效率增大。     

On the theory of stationary velocity of propagation of an exothermic reaction front in a condensed medium

It has been demonstrated experimentally that in the combustion of many explosives and powders in the condensed phase (k-phase) an exothermic chemical reaction occurs. Although the heat release in the k-phase is usually small in comparison with the calorific value, it may play an important role in the multistage reaction in the combustion zone.Analysis of the heat balance of the k-phase reveals that in a number of cases heating of the substance before gasification is primarily due to self-heating. According to the thermocouple measurements made by A. A. Zenin, the heat release in the k-phase during combustion of nitroglycerine N powder is more than 80% of the total quantity of heat in the heated layer of the k-phase (pressure 50 atm). This makes it possible to speak of the propagation of the exothermic reaction front in a condensed medium as the first stage in the combustion of condensed systems. Cases are also known where the propagation of the reaction front is maintained only by self-heating (flameless combustion [1]), and there are cases when such propagation is not accompanied by gasification (combustion of thermites, sometimes the polymerization process). Theoretical investigations of stationary propagation of a reaction front in a condensed medium were made in [2–6]. We note that this problem is also of interest in relation to the study of various nonstationary phenomena associated with the combustion of powders [7–9]. One of the principal theoretical problems is the derivation of a formula for the velocity of propagation of the reaction front in the k-phase. The Zel'dovich-Frank-Kamenetskii method [10] was used in [2–5] in the solution of this problem.This paper is an investigation of the applicability of the Zel'dovich-Frank-Kamenetskii method to the case of propagation of a zero-order reaction front in the k phase. A method is proposed for deriving a formula for the propagation velocity of the front leading in the case of a zero-order reaction to a formula identical to that obtained using the Zel'dovich-Frank-Kamenetskii method, and this method is then used to derive a formula for the propagation velocity of a first-order reaction front in the k-phase. The upper and lower limits of the velocity given by this formula are investigated.     

Multizone combustion of condensed systems

In the general case the combustion of condensed systems is of a stage-wise character and the combustion front is multizone [1, 2]. Following the investigation of two-zone models [3–5] it became clear that, during multizone combustion, one of the zones of heat evolution is the controlling zone. The velocity of the front is equal to the velocity of the controlling zone; however, with a change in the parameters of the system, there is the possibility of a transition of the controlling role from one zone to another, as well as of the coalescence and splitting of zones. This paper discusses a generalization of the two-zone problem which makes it possible to go over to the analysis of a complex, multizone front and shows that, for a front with two reactions (in the condensed phase and in the gas) and with dispersion, there are in all three possible arrangements of the zones of heat evolution (two three-zone variants and one two-zone variant). All possible types of dependence of the combustion rate on the depth of the dispersion are found.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 99–105, November–December, 1972.     

Structure of the heating layer ahead of the front of a strong intensely emitting shock wave

The problem of the structure and brightness of strong shock waves arises in the investigation of such phenomena as the motion of large meteoroids in the atmosphere, optical and electrical discharges, the development of strong explosions, and other similar processes and in the creation of powerful radiation sources based on them. This problem also has a general physics interest. As the propagation velocity of a strong shock wave increases the gas temperature behind its front and the role of emission grow. Part of the radiation emitted by the gas heated and compressed in a shock wave is absorbed ahead of the front, forming the so-called heating layer. The quasisteady structure of a strong intensely emitting shock wave was studied in [1, 2]. In this case a diffusional approximation and the assumption of a gray gas were used to describe the radiation transfer. They introduced the concept of a wave of critical amplitude, when the maximum temperature T_- in the heating layer reaches the temperature T_a determined on the basis of the conservation laws, i.e., from the usual shock adiabat; it is shown that behind a compression shock moving through an already heated gas there is a temperature peak in which the maximum temperature T₊ exceeds T_a. The problem of the quasisteady structure of an emitting shock wave in air of normal density was solved numerically in [3]. The angular distribution of the radiation was approximately taken into account — it was assigned by a simple cosinusoidal law. The spectral effects were taken into account in a multigroup approximation. They introduced 38 spectral intervals, which is insufficient to describe a radiation spectrum with allowance for the numerous lines and absorption bands.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 86–92, September–October, 1978.     

Supersonic flow of combustible gas mixture past sphere with account for ignition delay time

Assume an axisymmetric blunt body or a symmetric profile is located in a uniform supersonic combustible gas mixture stream with the parameters M₁, p₁, and T₁. A detached shock is formed ahead of the body and the mixture passing through the, shock is subjected to compression and heating. Various flow regimes behind the shock wave may be realized, depending on the freestream conditions. For low velocities, temperatures, or pressures in the free stream, the mixture heating may not be sufficient for its ignition, and the usual adiabatic flow about the body will take place. In the other limiting case the temperature behind the adiabatic shock and the degree of gas compression in the shock are so great that the mixture ignites instantaneously and burns directly behind the shock wave in an infinitesimally thin zone, i. e., a detonation wave is formed. The intermediate case corresponds to the regime in which the width of the reaction zone is comparable with the characteristic linear dimension of the problem, for example, the radius of curvature of the body at the stagnation point.The problem of supersonic flow of a combustible mixture past a body with the formation of a detonation front has been solved in [1, 2]. The initial mixture and the combustion products were considered perfect gases with various values of the adiabatic exponent .These studies investigated the effect of the magnitude of the reaction thermal effect and flow velocity on the flow pattern and the distribution of the gasdynamic functions behind the detonation wave.In particular, the calculations showed that the strong detonation wave which is formed ahead of the sphere gradually transforms into a Chapman-Jouguet wave at a finite distance from the axis of symmetry. For planar flow in the case of flow about a circular cylinder it is shown that the Chapman-Jouguet regime is established only asymptotically, i. e., at infinity.This result corresponds to the conclusions of [3, 4], in which a theoretical analysis is given of the asymptotic behavior of unsteady flows with planar, spherical, and cylindrical detonation waves.Available experimental data show that in many cases the detonation wave does not degenerate into a Chapman-Jouguet wave as it decays, bur rather at some distance from the body it splits into an adiabatic shock wave and a slow combustion front.The position of the bifurcation point cannot be determined within the framework of the zero thickness detonation front theory [1], and for the determination of the location of this point we must consider the structure of the combustion zone in the detonation wave. Such a study was made with very simple assumptions in [5].The present paper presents a numerical solution of the problem of combustible mixture flow about a sphere with a very simple model for the structure of the combustion zone, in which the entire flow behind the bow shock wave consists of two regions of adiabatic flow-an induction region and a region of equilibrium flow of products of combustion separated by the combustion front in which the mixture burns instantaneously. The solution is presented only for subsonic and transonic flow regions.     

Wave propagation in the combustion of a low-concentration aerial suspension

In the general case the convective combustion of aerial suspensions is described by the equations of mechanics of multiphase media [1]. If the volume particle content is neglected and it is assumed that in the initial stage of convective front propagation the particles are stationary, and that during combustion their temperature is constant, then the equations for describing the combustion process reduce to the equations of gas dynamics for a distributed supply of heat and mass [2, 3]. The equations and model constant mass burning rate kinetics are used to solve the plane one-dimensional problem of the combustion of an aerial suspension in part of a region bounded on one side by a fixed wall. A small parameter proportional to the mass concentration and the heat value of the fuel is introduced. The method of matched asymptotic expansions [4] is used to construct a uniformly applicable first approximation. The solution obtained describes the wave propagation in aerial suspension combustion processes. The resulting pattern includes an inclined compression wave propagated with the speed of sound followed by a convective hot reaction product front whose propagation velocity is much less (in conformity with the small parameter introduced) than the speed of sound.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 63–73, March–April, 1986.     

The pressure and temperature behind bodies with flat bases in a supersonic flow when inert and active gases are introduced into the base region

The effect of introducing active and inert gases into the base region behind two-dimensional and axisymmetric bodies on the pressure and temperature in that region is studied in the absence of heat transfer between the body and the base region. The flow in the mixing zone is assumed to be turbulent. To investigate the effect of introducing active gases on the parameters in the base region, a model of diffusion combustion is used. The base pressure is calculated by Korst's method [1]. For the velocity profile in the mixing zone an expression is used which results from integrating the equation of motion in von Mises variables. The temperature and concentrations of the components in the base region are determined from integral equations for the conservation of enthalpy and concentration, which make it possible to calculate the parameters in the base region for arbitrary flow rates of the active gas, including arbitrarily small rates. The results are given of calculating the base pressure when hydrogen and argon are blown into the base region. In the latter case computational and experimental results are compared.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 48–57, March–April, 1971.     

Influence of anisotropy of the permeability on the convection and heat transfer in a porous annular layer

Investigations into the convective transport of heat in porous materials are of interest for many applications in connection with the problem of increasing the efficiency of thermal insulation. In [1–5], convection in Isotropic porous media was considered. However, in many cases porous materials have an essential anisotropy of their permeability. Convective heat transfer has been inadequately studied for this case. In [6], the linearized equations were used to study the convection between infinite horizontal planes with a filling of an anisotropic material; the value of the critical Rayleigh number was found, and this agreed satisfactorily with experimental data. In the present paper, we investigate numerically convection between two infinite coaxial cylinders with an anisotropic porous filling, using the equations of convection in the Darcy—Boussinesq approximation [1–3]. The permeability tensor in the annular region is constructed from its principal values, which can be found experimentally. A method of calculation is developed and a parametric study made of the structure of the flow and of the local and averaged characteristics of the heat transfer, which are of interest for the design of thermal insulation.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 59–64, January–February, 1980.     

Mathematical model of water-steam phase transitions in hydrothermal reservoirs

The problem of steam production from a water-saturated hydrothermal reservoir is considered. It is shown that the introduction of a evaporation surface separating the gas and liquid phases leads to superheating of the water in a zone ahead of the front. This contradiction is removed by introducing of an extended phase transitions zone between the single-phase zones. In this case the problem contains two unknown moving boundaries considered as surfaces of discontinuity of the moisture content.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, pp. 98–105, November–December, 1994.     

Depeletion of the elastic reserve of a sealed and fractured formation with anomalously high formation pressure

Analysis of the exploitation of deposits with anomalously high formation pressures has shown [1] that when the weighted-mean formation pressure drops below a certain critical value (close to the hydrostatic pressure) a rather sharp sudden fall in output, together with a change in the rate of decline of pressure, is observed. The fall in output is attributable to the closing of the joints and the resulting catastrophic deterioration in the permeability of the reservoir [2]. In this paper an attempt is made to develop a joint closing hypothesis, to calculate the motion of the joint closing front from the bottom of the well to the edge of a homogeneous circular formation, and to derive expressions for predicting the fall in the output of the wells and the pressure in the formation. In order to obtain solutions it is assumed that the reservoir depletion regime is quasisteady, so that the results should be regarded as approximate.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 73–83, November–December, 1985.     

Radiative and convective heat transfer in hypersonic flow around a blunt body

The heat transfer in the vicinity of the critical point is investigated for hypersonic air flow around a blunt body. The gas-dynamical conservation equations are solved simultaneously with the radiative transport equation in integral form. Allowance is made for the viscosity, heat conduction, and the actual radiation parameters of air, including spectral line emission. Profiles are obtained for the thermodynamic variables along the critical line. The dependence of the radiative and convective components of the aerodynamic heating on the velocity and pressure ahead of the shock front as well as the radius of curvature of the blunt nose section is discussed. Approximate relations having the form of similarity laws are derived for the heat fluxes in the vicinity of the critical point. The limits of applicability of the thermodynamic equilibrium approximation in the shock-compressed layer are discussed. The influence of absorption of radiation from the compressed layer by the cold freestream on the aerodynamic heating is considered. Attention is given in this case to the dependence of the spectral absorption coefficient for the cold air on the intensity of the radiation incident upon it.Moscow. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 112–123, September–October, 1972.     

Convection of a viscous incompressible gas in rectangular regions with inlet and outlet channels

A study is made of two-dimensional problems of thermal convection of a viscous incompressible gas in rectangular regions that have gas inlet and outlet channels in the presence of a temperature difference between the bottom and the top (the bottom is heated). In contrast to the well-studied case of natural convection, when no-slip conditions are specified on all boundaries of the region and motion in the region occurs only through the temperature difference [1–4], the heat transfer in the investigated flows is complicated by the additional influence of the forced convection of the gas due to the motion of gas through the inlet and outlet channels. Flows of such type simulate well the processes that take place in many heat transfer devices and in ventilated and air-conditioned industrial premises. Two formulations of the problem are considered. In the first, the gas flow through the inlet and outlet channels is assumed given, and the solution of the problem is determined by the dimensionless Prandtl, Grashof, and Reynolds numbers. In the second case, this flow rate is not given but determined during the solution of the problem. The motion in the region arises from the difference between the temperatures of the bottom and the top of the region, and the motion, in its turn, causes a flow of gas through the inlet and outlet channels. As in the case of natural convection, the solution of the problem in this case is determined by only two dimensionless numbers — the Grashof and Prandtl numbers. By numerical solution of the boundary-value problems for the equations of heat transfer a study is made of the influence of the characteristic dimensionless numbers on the hydrodynamic and temperature fields and the heat fluxes through the boundaries of the region. The solutions of the problems in the two formulations are compared for different positions of the outlet channels.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 126–131, September–October, 1979.We thank G. I. Petrov for discussing the results.     

A pore scale study on turbulent combustion in porous media

This paper presents pore scale simulation of turbulent combustion of air/methane mixture in porous media to investigate the effects of multidimensionality and turbulence on the flame within the pores of porous media. In order to investigate combustion in the pores of porous medium, a simple but often used porous medium consisting of a staggered arrangement of square cylinders is considered in the present study. Results of turbulent kinetic energy, turbulent viscosity ratio, temperature, flame speed, convective heat transfer and thermal conductivity are presented and compared for laminar and turbulent simulations. It is shown that the turbulent kinetic energy increases from the inlet of burner, because of turbulence created by the solid matrix with a sudden jump or reduction at the flame front due to increase in temperature and velocity. Also, the pore scale simulation revealed that the laminarization of flow occurs after flame front in the combustion zone and turbulence effects are important mainly in the preheat zone. It is shown that turbulence enhances the diffusion processes in the preheat zone, but it is not enough to affect the maximum flame speed, temperature distribution and convective heat transfer in the porous burner. The dimensionless parameters associated with the Borghi–Peters diagram of turbulent combustion have been analyzed for the case of combustion in porous media and it is found that the combustion in the porous burner considered in the present study concerns the range of well stirred reactor very close to the laminar flame region.     

Front Regime of Heat and Mass Transfer in a Gas Hydrate Reservoir under the Negative Temperature Conditions

The analytical self-similar solution to the nonlinear problem of the front regime of heatand- mass transfer in a gas hydrate reservoir under the negative temperature conditions is obtained. In the initial state the reservoir is assumed to be saturated with a heterogeneous gas hydrate–ice–gas mixture. In particular cases there may be no ice or/and gas. The ice and gas are formed behind the gas hydrate dissociation front. The calculations are presented for a stable hydrate–gas system. The critical curves are constructed in the well-pressure–reservoir-permeability plane. These curves separate the domains of the front regime and the regime of volume gas hydrate dissociation ahead of the front. The velocity of the gas hydrate dissociation front is investigated as a function of various problem parameters. The characteristic temperature and pressure distributions corresponding to various regimes on the diagram are investigated.     

Convective combustion of aerosuspensions in fuel that contains the oxidant

The convective combustion of porous gunpowder and high explosives is an intermediate stage in the transition from layered combustion to detonation [1, 2]. The theory of convective combustion of such systems is developed in [3–6]. It has now become necessary to analyze the possibility of convective combustion of aerosuspensions. The present paper develops the theory of the combustion of such systems on the basis of an analysis of the equations of gas dynamics with distributed supply of mass and heat; the problem of nonstationary motion of a convective combustion front is formulated. In the homobaric approximation [7], when the pressure is assumed to be spatially homogeneous, an analytic solution to the problem is found; this determines the law of motion of the front and the distribution of the parameters that characterize the gas and the particles in the combustion zone. Necessary conditions for the transition from convective combustion to explosion are obtained.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 49–56, September–October, 1980.I thank R. I. Nigmatulin for helpful comments and advice, and also V. A. Pyzh and V. K. Khudyakov for discussing the work.     

Convective heat transfer in the melt in Czochralski growth of garnet-structure single crystals

The results of investigating the hydrodynamic processes in the melt during garnet-structure Czochralski crystal-growing (yttrium-aluminum garnet single crystals 25–40 mm in diameter) using an induction heater are presented. A mathematical model of the hydrodynamics and heat transfer in the melt based on the two-dimensional Navier-Stokes equations in the Boussinesq approximation is proposed. The effect of the convective heat transfer on the shape of the crystallization front, which is an important characteristic of the quality of single crystals, is determined in terms of the rotation velocity of the crystal and the induction heating parameters.Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 29–38, July–August, 1995.     

Stability of heat transfer regimes at the front stagnation point of a body in a stream of dissociated gas

The formulation and solution of the stationary problem of heat transfer in the neighborhood of the front point of a body at constant temperature in a stream of dissociated air are given in [1]. In [2], the results are given of numerical solution of this problem in the nonstationary formulation; the establishment of a stationary heat transfer regime was established for all the calculated variants. In the present paper, we investigate the stability of stationary heat transfer regimes at the front stagnation point of a body in a stream of dissociated air using the Lyapunov functional method [3, 4] and the method of [2, 5], which is based on the use of Meksyn's method in boundary-layer theory [6, 7]. It is established that an arbitrarily strong growth of the Damköhler number does not lead to instability and multiplicity of the stationary regimes, in contrast to the case when a hot mixture of gases flows over the front point of a thermostat [2, 5, 8]. Numerical solution of the boundary-layer equations for a wide range of Damköhler numbers confirms the results of the approximate qualitative analysis and shows that in a number of cases the time of establishment of the stationary state is a nonmonotonic function of the Damköhler number.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 97–106, September–October, 1979.     

Friction and heat transfer with simultaneous convection on a permeable surface

The velocity and heat transfer fields near a vertical permeable surface with simultaneous convection are investigated. A solution is found for the boundary layer equations with known laws of surface temperature and flow velocity change. The transformed boundary layer equations contain the parameter G/R², which determines the effect of free convection on friction and heat transfer for constrained motion. Calculations of friction and heat transfer as functions of draft (suction) with simultaneous convection are presented.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 96–100, March–April, 1973.     

Motion of a nonisothermal adsorbable mixture with enhanced values of the concentrations through a porous medium

The equations of motion of a nonisothermal adsorbable mixture with enhanced values of the concentrations of the components in the case of infinitely large coefficients of heat and mass transfer reduce to a hyperbolic quasilinear system of equations. The invariant solutions of this system are analyzed. Convexity conditions are obtained under which a traveling-wave regime is realized in the porous medium. A system of equations is found for determining the concentrations of the adsorbable components of the mixture when a self-similar regime of dispersing waves is realized. For the case of finite values of the coefficients of heat and mass transfer, expressions are given for the width of the stationary front in the traveling-wave regime.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 76–86, September–October, 1980.     

Numerical modeling of thermocapillary convection in a fluid layer with local heating of the free surface

Thermocapillary convection in a plane horizontal fluid layer with concentrated heating of the free surface is modeled numerically using the Navier-Stokes equations and the heat transport equation. This makes it possible to examine the structure of the convection throughout the fluid volume, in particular in the region where the motion is weak. The deformation of the free surface is assumed to be negligibly small. In the case of a ponderable fluid this assumption is justified given certain upper and lower constraints on the temperature difference and the thickness of the layer, respectively, [9, 10]. Under conditions of weightlessness a fluid layer of constant thickness in a rectangular channel can be realized at a contact angle of 90° [7].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 108–113, July–August, 1987.