PECULIARITIES OF AERODYNAMIC COMPUTATIONS OF VENTILATION SYSTEMS IN THE COMPUTER PROGRAM MAGICAD

Abstract

One of the most popular computer programs for designing interiorengineering systems for buildings, including ventilation systems, isthe MagiCAD program of the Finnish company MagiCAD Group.MagiCAD allows easily and quickly create three-dimensional modelsof ventilation systems, selecting area sections of air pipelinessections, to perform aerodynamic and acoustic calculations andbalancing of air duct networks, making detailed specifications and etc.Despite the detailed documentation on the program, the MagiCADmechanism remains hidden from the user.The method of pressure losses definition in MagiCAD is significantlydifferent from the national standards, especially for definition ofpressure losses of components. This difference should be taken intoaccount when doing aerodynamic computations designing ventilationsystems. The paper considers the mathematical dependencies usedby the MagiCAD program for aerodynamic computations of airpipelines. The comparison of these dependencies with the used fornational design practice is also provided in the paper. The comparisonof computation results is made for specific values of friction pressure losses, pressure losses of components such as bends of round andrectangular sections of different angles, diffusers and confusers, teefittings, etc.Despite the significant differences in the methods, the computedvalues of the pressure losses are quite close, the significantdifferences in the results of the calculations were observed only forconfusers. Obviously, significant differences can be expected in theresults of the calculation of the distribution nodes operating in thepressure (flow separation) mode, since its computation according toBCH 353-86 is similar to the confusers’ computation, but this issueneeds further research.