Indexed on: 17 Apr '14Published on: 17 Apr '14Published in: Thermal Engineering
Maintaining the preset distribution of coolant mass flow rate at the outlet from the header system organized as a back turn with lateral admission of coolant to the header and central removal of coolant from it is one of the conditions essential for securing reliable and efficient operation of a reactor plant. In the header system, coolant passes through the annular lateral channel formed by the vessel and central barrel, after which it enters into the header, changes the motion direction in it, and goes out through the channels of the grid placed in the central barrel. The results obtained from experimental investigations of the hydrodynamics in the header system flow paths carried out on models with flat and cylindrical shapes are presented. A previously unknown regularity pertinent to formation of hydraulic irregularities at the header system outlet is revealed, and semi-empirical correlations for determining the coolant mass flow rate distribution at the header system outlet are obtained. The regularity connected with formation of hydrodynamic nonuniformities at the header system outlet lies in the fact that the position of the maximum coolant velocity at the grid outlet coincides with the position of the maximum velocity in the core of the incident jet attacking the grid, and that the maximal average coolant velocity in the grid holes is proportional to the average coolant velocity in the incident jet.