ANALYSIS OF AERODYNAMIC CHARACTERISTICS IN THE TUNNEL KILN CHANNEL WHEN CHANGING THE GEOMETRIC CHARACTERISTICS OF THE CHANNEL

Стаття присвячена аналізу впливу зміни висоти каналу тунельної печі на її аеродинамічні характеристики шляхом моделювання розподілення швидкостей та тисків повітря та пічних газів. Було розглянуто 3 варіанти геометрії тунелю: базовий, зі зниженою висотою в зоні випалу та зі зниженою висотою по всій довжині печі. В результаті моделювання отримано залежності статичного тиску по довжині печі та швидкості руху пічних газів по її висоті. Проведений аналізу зміни швидкості пічних газів в тунелі надав можливість стверджувати, що найбільш ефективним з точки зору рівномірності розподілення швидкості є варіант із зниженням висоти склепіння по всій довжині печі. Ключові слова: тунельна піч, канал тунельної печі, зміна геометрії печі, моделювання розподілення швидкостей, розподілення статичного тиску.The article is devoted to the analysis of the influence of tunneling channel height change on its aerodynamic characteristics by modeling the velocity and pressure distribution of air and furnace gases. Three variants of the tunnel geometry were considered: basic, with reduced height in the firing zone and with reduced height along the entire length of the furnace. The simulation results in the dependence of the static pressure along the length of the furnace and the velocity of the furnace gas moving along its height. The analysis of the change in the velocity of the furnace gases in the tunnel has made it possible to say that the most effective in terms of uniformity of velocity distribution is the variant with the reduction of the height of the arch along the entire length of the furnace.Keywords: tunnel kiln, tunnel kiln channel, change of kiln geometry, velocity distribution modeling, static pressure distribution

Simulation of the Distribution of Air Flows and Fuel Combustion Products in A Channel of A Tunnel Kiln

A characteristic problem of the operation of tunnel kilns with high overlap is the output of products with low quality and a decrease in the energy efficiency of the burning process as a whole. Therefore, the object of research is the process of the flow of kiln gases through the channel of the tunnel kiln, the change in velocity of which was studied depending on the geometric parameters of the tunnel.In the course of studies of the dependence of the velocity distribution of the flow of kiln gases along the channel of the kiln on its geometric characteristics, a numerical simulation method in a simplified 2D formulation using the OpenFoam open code using the k--shear stress turbulence model is used. The velocity fields of kiln gases are obtained for three options for the height of the channel: the base with a vault height of 2 m, with a reduced vault height along the entire length of the tunnel and with a reduced tunnel height only in the burning zone. Analysis of changes in flow rates shows that the most effective would be to reduce the height along the entire kiln length, while changing the arch height in the burning zone will hardly affect the uniformity of velocities in the heating zone. Reducing the arch height also minimizes the likelihood of a return air flow in the cooling zone in the area from burning to the place of air extraction for drying. A lower overlap in the cooling section will increase the intensity of heat removal and, accordingly, reduce its loss with the product in order to use it for drying products.The presented simulation results make it possible to note that a change in the height of the overlap will lead to an increase in aerodynamic drag and, consequently, a pressure drop. This will require additional energy costs for driving draft engines and the possibility of increasing temperatures in the space under the cars