Decrease of pressure losses in elbow fittings of ventilation systems of thermal power plant buildings

Abstract

The paper presents the results of a numerical study of the flow in the elbows of the ventilation systems in buildings of thermal power plants. Elbow fittings, as well as other shaped elements of ventilation systems are the main causes of energy losses. A method is proposed for reducing such losses through the use of an insert profiling the sharp edge of the elbow along the outline of the vortex zone. For a wide range of practical dimensions, numerical models of “sharp” elbows at 90° have been studied, a good correspondence between pressure losses in them, numerical and known experimental data has been shown. The outlines of the vortex zones, as well as the lengths of the influence zones of the elbow on the flow parameters upstream and downstream, are determined. Next, numerical models of profiled elbows are constructed and studied; a significant reduction in pressure losses (up to 64%) and lengths of influence zones (up to 45%) as compared with unprofiled ones is shown. Dependence has been found to determine the local resistance coefficient of the profiled elbow, which can be used in the design of ventilation systems.