Showing papers in "Journal of Applied Mechanics and Technical Physics in 1978"

Stability of boundary layer of catalytically recombining gas

Abstract: where u is the gas flow velocity in the boundary layer; p is the density; T is the temperature; c is the degree of dissociation; ~ is viscosity; Cp and c v are the specific heat capacities at constant pressure and volume; ~ = Cp=/Cv=; M= is theMaeh number at the outer edge of the boundary layer; Pr is the Prandtl number; Sc is the Schmidt number; Re is the Reynolds number; e is the wave number; C is the phase velocity for perturbation propagation; f, ~ , ~, r, ~ , and y are amplitude functions of the pulsations of the quantities u, v/e, p, p, T, and c, respectively; p is the pressure; v is the transverse component of the velocity. Primes denote differentiation with respect to the transverse coordinate y and the subscript ~ denotes values of quantities at the outer edge of the boundary layer, along which some of the quantities are scaled. Thermal diffusion is neglected.

Nonstationary processes in starting strongly underexpanded jets

Abstract: Results of the investigation of nonstationary efflux of argon by the electron-beam-sounding method are presented in [1]. Comparing the regularities obtained in that paper for the front motion of material during efflux from a nozzle with computations [2] for nonstationary expansion from a spherical source and the experimental results in [3] permitted clarification of the singularities of the influence of counter pressure and the temperature factor in jet expansion. The density distribution in nonstationary nitrogen and argon jets is obtained in this paper and study of the regularities of the front motion of the escaping gas is continued.

Thermoelastic axisymmetric problem for a two-layer cylinder

Abstract: The majority of devices and units of microelectronics are multilayer structures made of materials with differing coefficients of thermal expansion and elastic constants. Thermal stresses which arise in such systems due to temperature changes when manufactured or in operation may result in a breakdown, or plastic deformation or in a change of the physical properties of materials. At the same time, due to adopted assumptions the existing design models do not describe the stressed states in real systems of finite dimensions. The designs in [1–3] are obtained on the basis of the engineering theory of beams, and in [4, 5] the obtained solution was for the infinite strip in a half-space. In the present article a right circular cylinder of radius R was used as a mathematical model which was cut by the plane z = 0 into two layers of thickness H or H* (Fig. 1). In our considerations the quantities referring to the layer 2 are distinguished by an asterisk. The cylinder deformation problem due to the temperature lowering from t1 to T2 was solved within the framework of the linear theory of thermoelasticity. It was assumed that the material of each layer is homogeneous and isotropic, that the temperature is independent of the coordinates, and that the coefficients of thermal expansion α and α* are independent of T. Two formulations are analyzed.