АЕРОДИНАМІКА ПОВІТРЯНОГО ПОТОКУ ПОБЛИЗУ КОНІЧНОЇ ДИМОВОЇ ТРУБИ НА МАЙДАНЧИКУ ТЕПЛОВОЇ ЕЛЕКТРОСТАНЦІЇ

• Дата: 2022
• Автори: Chyrkova, A. P., Shikhabutinova, O.V.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: Institute of Engineering Thermophysics of NAS of Ukraine 2022
• Онлайн доступ: https://ihe.nas.gov.ua/index.php/journal/article/view/512
• Назва журналу: Thermophysics and Thermal Power Engineering

The chimney at the industrial site of the TPP ensures the release of gaseous combustion products into the atmosphere. With the correct organization of the gas outlet, moisture condensation does not occur in the middle of the pipe and the technical condition of the pipe remains in working order for a longer period of time. When analyzing the operating conditions and determining the temperature of the combustion products inside the pipe, it is necessary to know the boundary conditions of the third kind (heat transfer coefficients) on the outer surface of the chimney. The external flow around the smoke pipe has a complex character with a vortex structure in the aft part. The wind speed profile in front of the conical pipe is determined by the type of surrounding surface near the TPP. Studies have shown that even with a uniform velocity profile of the flow impinging on the pipe, the aerodynamics and heat exchange on the surface of a single vertically located conical pipe have specific features due to the shape of the pipe and the contact of its base with the earth's surface. Purpose. The purpose of the work is to determine the characteristics of the aerodynamics of the air flow when flowing around a single conical pipe located on the industrial site of the TPP with different wind directions. The research was carried out by the method of computer modeling with the numerical solution of the differential equations of motion and continuity. Materials and methods. To simulate the aerodynamics near the chimney located on the territory of the TPP, the simplified infrastructure of the site was used in the work, which includes the main elements - a machine room (height 30 m), a substation, an administrative building, a warehouse and two cooling towers. The size of the TPP site from south to north is 295 m, from east to west - 247 m. The smoke pipe has a diameter at the base D = 15 m and a taper of 0.0625 (at the mouth diameter d = 7.5 m), the height of the pipe is 120 m. Smoke pipe is placed asymmetrically in relation to the engine room building. Three wind directions were studied in the work. Two seasons of TPP operation (autumn, winter) with different air temperature and wind direction are considered. The wind speed was 5 m/s. The speed profile at the boundary of the TPP site was determined according to the urban infrastructure type of the surrounding space around the TPP site. The wind speed profile for these conditions was given by the equation wz = w0 k (z), де wz – flow velocity at height z from the surface of the earth, w0 – wind speed at the border of the TPP territory, coefficient k(z) is determined by dependence k(z) = 0.4 (z/10)0.5. Results. In the first variant (the wind blows from the east) during the autumn period, a slight influence of the engine room building on the aerodynamics and heat transfer of the chimney was observed (the chimney is in front of the engine room building). If the wind direction is south (option 2), the flow has the character of a poorly streamlined body, with flow separation on the side surfaces and the roof of the engine room. Analysis of the aerodynamics of the flow around the pipe on the side above the engine room building shows the periodic nature of the distribution of flow velocity (and static pressure) along the height of the pipe, just as in the case of flow around a single pipe. In this case, a fairly low heat exchange between the pipe and the oncoming flow should be expected. Option 3 is similar to option 2. The aerodynamics of the flow around the engine room and smoke pipe from the side are given. The analysis shows that, just as with the northerly direction of the wind, periodic fluctuations of the speed (and static pressure) are observed in the aft area at the height of the pipe above the engine room building, and the mouth of the pipe flows at a high speed. Conclusions. The infrastructure of the TPP area significantly affects the aerodynamics of the air flow near the conical chimney. For the first time, the periodic nature of the change in speed and static pressure along the height of the pipe in the aft area above the engine room building was revealed. When the wind direction is south, a complex vortex structure is formed on the surface of the pipe in the area of ​​the engine room in the absence of a boundary layer on the surface of the pipe. In the latter case, the highest heat transfer from the pipe surface to the oncoming flow should be expected. Due to the complex aerodynamics for the pipe in the conditions of the infrastructure of the territory of the TPP, the similarity equation for the average heat transfer can give large errors when calculating the external heat exchange.