Thermoelastic Response of Closed Cylindrical Shells in a Supersonic Gas Flow

The work is devoted to the investigation of flutter oscillations and the stability of the closed cylindrical shell in supersonic gas flow in an inhomogeneous temperature field. It is assumed that supersonic gas flows on the outside of the shell with an unperturbed velocity U, directed parallel to the cylinder generatrix. Under the action of an inhomogeneous temperature field the shell bulges out, this deformed state is accepted as unperturbed, and the stability of this state is studied. The main nonlinear equations and relationships describing the behavior of the examined system are derived. The formulated boundary value problem is solved using the Galerkin method. The joint influence of the flow and the temperature field on the relationship between the amplitude of nonlinear oscillations of a cylindrical shell and the speed of the flowing stream is studied. The critical velocity values are calculated from the corresponding linear system and are given in tables. The numerical results show that: (a) the surrounding flow significantly affects the nature of the investigated relationship; (b) a certain interval of supersonic velocity exists where it is impossible to excite steady-state flutter oscillations (the silence zone); (c) the dependence of amplitude on the supersonic velocity can be either multivalued or single-valued.

Supersonic gas flow impacting approach for solid-state synthesis at room-temperature: Temperature measurement

Solid-state synthesis based on supersonic gas flow impingement at room-temperature is an alternative approach to traditional mechanochemical preparation. The supersonic airflow is generated by a convergent-diffusion nozzle with a design Mach number of 3.0. The solid material particles from the suction pipe in the coaxial nozzle can get very high kinetic energy in microseconds. Then the particles impact the target or collide with each other to achieve the transfer of kinetic energy to thermal or chemical energy. We utilize the infrared technology to successfully measure the solid particles’ temperature while they impact the target after gathered energy from the supersonic air gas. The results show that the average temperature of the silicon particles with an average particle diameter of 150 [Formula: see text]m after impacting the target is about [Formula: see text]C, and some of the temperature exceed [Formula: see text]C. It dedicates that the kinetic energy of the particles during the collision translate into internal energy indeed. The work of this paper lays a good foundation for further research on the low-temperature solid-phase reaction processes.