O. V. Sharypov

Flow diagnostics in a vortex furnace by particle image velocimetry

The internal aerodynamics of a model vortex furnace for a steam generator with a horizontal axis of flow rotation and distributed input of fuel-air mixture jets has been studied. Average characteristics of the flow velocity field in various cross sections have been determined using a digital tracer imaging (particle image velocimetry) technique. Results are compared to data obtained by the method of laser Doppler anemometry.

Modeling of pulverized coal combustion processes in a vortex furnace of improved design. Part 1: Flow aerodynamics in a vortex furnace

Some results of the complex experimental and numerical study of aerodynamics and transfer processes in a vortex furnace, whose design was improved via the distributed tangential injection of fuel-air flows through the upper and lower burners, were presented. The experimental study of the aerodynamic characteristics of a spatial turbulent flow was performed on the isothermal laboratory model (at a scale of 1 : 20) of an improved vortex furnace using a laser Doppler measurement system. The comparison of experimental data with the results of the numerical modeling of an isothermal flow for the same laboratory furnace model demonstrated their agreement to be acceptable for engineering practice.

Visualization of flow structure in a vortex furnace

The spatial structure of a swirling flow in a model vortex furnace with distributed input of fuel-air-mixture jets has been studied. The results of experimental and numerical investigations of a three-dimensional (3D) field of time-averaged velocities in an isothermal laboratory model of a vortex furnace have been used to image the structure of flow. Vortex structures have been identified using λ2 and Q criteria, as well as the concept of “minimum total pressure.” The vortex core of the flow has a V-shaped 3D structure.

Aerodynamics of a promising vortex furnace design

The aerodynamics of a promising vortex furnace design with secondary top blasting has been studied. Flow velocity fields have been measured in an isothermal laboratory model of the furnace using a digital tracer imaging (particle image velocimetry) technique. Three-dimensional diagnostics of flow structure in the combustion chamber has been carried out by the method of laser Doppler anemometry. Processing of the obtained data using the criterion of “minimum total pressure” has been used to visualize the spatial structure of the vortex core.

Study of aerodynamic structure of flow in a model of vortex furnace using Stereo PIV method

The aerodynamic structure of flow in a lab model of a perspective design of vortex furnace was studied. The chamber has a horizontal rotation axis, tangential inlet for fuel-air jets and vertical orientation of secondary injection nozzles. The Stereo PIV method was used for visualization of 3D velocity field for selected cross sections of the vortex combustion chamber. The experimental data along with “total pressure minimum” criterion were used for reconstruction of the vortex core of the flow. Results fit the available data from LDA and simulation.

Modeling of pulverized coal combustion processes in a vortex furnace of improved design. Part 2: Combustion of brown coal from the Kansk-Achinsk Basin in a vortex furnace

This paper continues with the description of study results for an improved-design steam boiler vortex furnace, for the full-scale configuration of which the numerical modeling of a three-dimensional turbulent two-phase reacting flow has been performed with allowance for all the principal heat and mass transfer processes in the torch combustion of pulverized Berezovsk brown coal from the Kansk-Achinsk Basin. The detailed distributions of velocity, temperature, concentration, and heat flux fields in different cross sections of the improved vortex furnace have been obtained. The principal thermoengineering and environmental characteristics of this furnace are given.

A description of the self-sustained evaporation-front shape in a layer of metastable liquid

A theoretical model for description of a stationary surface of the self-sustained evaporation front propagating in a layer of superheated liquid flowing over a flat heater is proposed, which takes into account new experimental data. An approximate analytical dependence of the vapor-layer thickness on the coordinate and physical parameters is obtained that satisfactorily agrees with the experimental results. A dimensional parameter is introduced that allows the description to be presented in an invariant dimensionless form.

Effect of disperse phase on instability in systems with combustion

The dynamics of weak perturbations with finite amplitude in a two-phase homogeneous medium (gas with suspended solid particles) featuring a nonequilibrium chemical reaction has been studied. Using an asymptotic approach, a weakly nonlinear model of the evolution of one-dimensional perturbations is developed that takes into account the kinetic wave interactions and dissipative properties including the interphase exchange of heat and momentum. Conditions for the loss of stability of the homogeneous state of the system are analyzed. Numerical solutions of the evolution equation are obtained in the form of established self-sustained oscillations. The stabilizing effect of the inert disperse phase is described.

Thermal-wave-induced vorticity in a liquid film

We have theoretically studied the influence of a moving local heat source on the structure of flow in a thin liquid layer on a horizontal substrate. A two-dimensional problem is considered in the boundary layer approximation and a stationary equation that describes deformation of the liquid layer is obtained. Results of numerical calculations for a preset temperature distribution on the free surface are presented that demonstrate the formation of a vortex structure. It is established that, even in the absence of a gravity-driven flow, the motion of a local heat source ensures a stationary flow regime without film breakage and the formation of dry spots. The results justify a new scheme of experiments for the investigation of phenomena in nonisothermal liquid films.

Instability of a two-dimensional film flow with inhomogeneous temperature field on the free surface

It is shown that a two-dimensional stationary flow of a thin liquid film with inhomogeneous temperature distribution on the free surface exhibits a local longwave instability. A critical condition for the transition to a regular three-dimensional flow with a “stream” structure is formulated and an expression for the characteristic period is derived.