Analysis of the velocity distribution in different types of ventilation system ducts

Abstract

The paper presents the results obtained during the preliminary studies of circular and rectangular ducts before testing the properties elements (elbows, tees, etc.)of rectangular with rounded corners ducts. The fundamental problem of the studies was to determine the flow rate in the ventilation duct. Due to the size of the channel it was decided to determine the flow rate based on the integration of flow velocity over the considered cross-section. This method requires knowledge of the velocity distribution in the cross section. Approximation of the measured actual profile by the classic and modified Prandtl power-law velocity profile was analysed.

Numerical simulation of minor losses coefficient on the example of elbows

“…Research group, to which the authors of this article belong, deals with the issue of minor losses in ventilation ducts. Initial results of research are presented in [10][11][12].…”

Building a bridge between industry and theory on the example of a new ventilation system

“…at the intersection of the rectangle's symmetry axis. Integration formula (3) over this duct quarter area was presented in [1,2]. Average velocity is determined by formula…”

“…Modification of power-law velocity profile consists in putting a squares into it, The formula (5) obtained as a result of integration of the distribution function over quarter of duct area (Fig. 3) was also presented in [1,2]. In the rounded rectangle, integration problem creates a cross-section area, i.e.…”

Modelling of air flow rate in significantly flattened rounded rectangular ventilation ducts

“…Based on empirical studies, it can be assumed that for large sections the model resulting from the modified Prandtl formula is superior to that of its original model. According to the modified Prandtl formula (power-law velocity profile), the flow velocity distribution along the coordinate is defined by the formula [1]  …”