Possibility of the occurrence of dissociation reactions of multiatomic molecules during rapid cooling in an expanding supersonic stream

We investigate the possibility of the occurrence of the reaction involving the dissociation of N₂O and the exchange reaction N₂O+CON₂+CO₂ during rapid cooling of a gas mixture due to supersonic expansion in a nozzle. A numerical solution of the equations for the balance of vibrational energy and the kinetics of the chemical reactions under nonequilibrium conditions is given. We find the values of the parameters that are necessary for the experimental observation of the phenomena considered.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 48–53, March–April, 1973.     

Combined heat and mass transfer in laminar gas stream flowing over an evaporating liquid film

A numerical analysis was carried out to study the detailed heat and mass transfer characteristics in laminar gas stream flowing over a falling liquid water film by solving the respective governing equations for the liquid film and gas stream together. It was observed that the cooling of the liquid film is mainly caused by the latent heat transfer connected with the vaporization of the liquid film. Significant liquid cooling results for the system with a high inlet liquid temperature, high gas stream velocity or a low liquid flowrate. Additionally, the predicted Nusselt and Sherwood numbers were correlated.     

Spatial distribution of CO2 dimers in axisymmetric gas jets expanding in a vacuum

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 1, pp. 56–62, January–February, 1989.     

Self-similar problem of separated ideal-fluid flow over an expanding plate

The research carried out in [1–8] is developed by considering the self-similar problem of the unsteady separated flow over a plate expanding from a point with the constant velocity D of a plane-parallel stream of ideal fluid with velocity V_∞. At infinity the flow is uniform, steady and normal to the surface of the plate. A wide range of values of the parameter α=V_∞/D is investigated. On the value of α there depends, in particular, the direction of shedding of the vortex sheets (VS) which, in accordance with the Joukowsky-Chaplygin condition, occur in separated flow over a plate. A comparison is made with the results obtained when the sheets are replaced by vortex filaments (VF). In accordance with [9] the choice of the intensity of the VF ensures, like the introduction of VS, the finiteness of the flow velocity at the edges of the plate. Within the framework of the unsteady analogy and the law of plane sections the problem of the flow over a delta wing at an angle of attack reduces to the unsteady flow over an expanding plate investigated. In addition to [3, 9], this question was also examined in [10–15]. In [11–15] and in [3] the analysis is based on VS and in [9, 10] on VF. Special attention is paid to the topology of the flow, in particular, to the structure of the so-called conical streamlines and their points of convergence and divergence (this was done in [3] for a special, nonlinear law of expansion of the plate and a variable free-stream velocity). The results obtained for the models with VS and VF are compared over a broad range of values of α, not only with respect to the integral characteristics, as in [12], but also with respect to the flow patterns. Moscow. Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 62–69, September–October, 1988.     

Submodel of rotational motions in gas dynamics

An invariant submodel of the equations of gas dynamics constructed on a one-dimensional subalgebra consisting of the sum of operators of rotation and translation in time is studied within the framework of the SUBMODELS program. The system of equations of the submodel is brought to symmetric form. Hyperbolicity conditions for the system are derived. Group analysis is performed and an invariant solution is considered. Isobaric flows are listed. For the simplest of them, characteristics and strong discontinuities are considered. Necessary conditions for existence of solutions without singularities on the axis are derived. Institute of Mechanics, Ural Scientific Center, Russian Academy of Sciences, Ufa 450000. Translated from Prikladnya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 6, pp. 37–45, November–December, 1998.     

Stability of one-dimensional gas flows in expanding regions

The stability of gas flows produced by the motion of a flat piston or the decay of an arbitrary discontinuity is considered. The boundaries of the region (or regions) in which the development of perturbations is considered are planes (shock wave, contact discontinuity, piston, etc.) which move away from each other.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 112–119, March–April, 1981.     

Theory of rotational relaxation in a diatomic gas

Journal of Applied Mechanics and Technical Physics - The three-dimensional problem of energy exchange between translational and rotational degrees of freedom in collisions of diatomic molecules...     

Spatial distribution of the gas phase in an axisymmetric submerged impact jet

Experimental data on the spatial distribution of the gas phase in an axisymmetric impact jet are obtained by the particle image velocimetry/laser-induced fluorescence (PIV/LIF) method. It is shown that the distribution of bubbles in the flow is determined by the dynamics of vortex structures. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 33–38, July–August, 2009.     

Finite element analysis of forming limit in bore expanding of aluminium alloy sheets

Summary A recently proposed method to predict the forming limit of sheet metals is applied to the problem of bore expanding. Axisymmetric bore-expanding processes of various aluminium alloy sheets are simulated by the rigid-plastic finite element method. From the calculated histories of stress and strain, the forming limit, i.e. the fracture initiation, is predicted by means of the ductile fracture criterion. The comparison with the experimental results shows that the fracture initiation site and the critical punch stroke are successfully predicted by the present approach. Received 23 February 1998; accepted for publication 12 May 1998     

Calculation of the pressure on the side surface of bodies consisting of a spherical segment joined to an inverted cone in a supersonic stream

The results of investigations of inviscid flow over inverted cones with nose consisting of a spherical segment were published for the first time in Soviet literature in [1–4]. In the present paper, a numerical solution to this problem is obtained using the improved algorithms of [5, 6], which have proved themselves well in problems of exterior flow over surfaces with positive angles of inclination to the oncoming flow. It is shown that the Mach number 2 M , equilibrium and nonequilibrium physicochemical transformations in air (H = 60 km, V = 7.4 km/sec, R₀ = 1 m), and the angle of attack 0 40° influence the investigated pressure distributions. A comparison of the results of the calculations with drainage experiments for M = 6, = 0-25° confirms the extended region of applicability of the developed numerical methods. Also proposed is a simple correlation of the dependence on the Mach number in the range 1.5 M of the shape of the shock wave near a sphere in a stream of ideal gas with adiabatic exponent = 1.4.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 178–183, January–February, 1981.     

Inverted population of Co2 molecules in expanding gas streams

The system of equations of hydrodynamics, which describes the process of escape of the mixtures CO₂ + N₂ + He, H₂O from a nozzle, is solved numerically in conjunction with the equations of the kinetics of the excitation of the vibrational degrees of freedom of the molecules. It is found that an inverted population of the CO₂ molecules with respect to the transition [00 °1] – [10 °0], is produced under certain conditions at the exit from the nozzle. The magnitude of the inversion depends both on the nozzle configuration and on the initial values of the gas temperature and pressure. It is shown that for a specified nozzle configuration there exist optimal values of these parameters, at which the inverted population of the CO₂ molecules reaches approximately 10¹⁵ cm^–3.Translated from Zhumal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 24–34, September–October, 1971.