Mathematical modeling of hydrodinamic processes in curvular channels of the confuser type

Abstract

The straight-line and curvilinear channels of the confusing type have been widely used in various fields of science and technology. Such channels can be used in the development of heat-exchange and turbine equipment, new types of wind turbines, etc. One of the important tasks to be solved in such a study is the choice of a channel geometry that provides minimal pressure loss, for example, when passing gas or air streams.

Nowadays engineering calculations are widely used for calculations in the field of computational hydrodynamics, heat and mass transfer, strength and other fields of technology. Among them, the important role is taken by the software package FLUENT, which is designed to simulate the complex flow of liquids and gases in a wide range of changes in the thermophysical properties using multi-layered methods that improve the convergence of computing processes.

The design of a channel of a confusing type, which has curvilinear walls, is considered. With such a channel design, the air enters the inlet, passes along a curved channel that narrows, and according to the Bernoulli law, the air velocity in the outlet will increase. Such channels can be used to increase the wind speed in wind turbine generators, which enables to increase the speed of rotor wind turbine and improve the efficiency of its operation. The curvilinear walls of the channel are chosen in such a way as to minimize the presence of gap zones in the channels and reduce aerodynamic losses in them.

The mathematical modeling of air mass transfer processes in the curvilinear channel of the confusing type is carried out using the Navier-Stokes equation in a two-dimensional formulation under the laminar flow regime, which is characteristic for the movement of air flows in channels of this type.

Numerical simulation of hydrodynamic processes in the curvilinear channel of the confusing type was performed using the CAD software ANSYS Fluent 18.2. A calculated grid in a channel that has chopping near the walls is constructed.

The distribution of the velocity field in the channel is presented. As follows from the received distributions, the maximum velocity values are observed at the end of the channel. At the surface of one of the walls, there is a stagnant zone in which the air moves at a very low speed due to the perpendicular direction of the air movement to the inlet.

As a result of numerical calculations, the local pressure distributions in the channel are obtained. As a result of the results, there is a drop in pressure at the exit of the channel. However, in quantitative terms the value of this fall is insignificant, which is due to the presence of curvature of the channel for the air channel duct.

Analysis of the received distributions of air velocity and pressure in the channel of the confusing type shows that the presence of curvilinearity of the walls of the channel leads to the absence of separation zones of air, which causes small pressure losses in the channels compared with the channels of other configurations. Channels of this type can be used in wind turbines, which will improve their aerodynamic characteristics, as well as the efficiency of wind energy use.

Numerical simulation of hydrodynamic processes in the curvilinear channel of the confusing type was carried out using the software package CAD ANSYS Fluent 18.2.

Local distributions of velocity and pressure fields are obtained. It is shown that the use of curvilinear channels reduces the presence of separation zones, reduces the loss of pressure, which improves the aerodynamic and energy characteristics of the wind turbine.