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Aerodynamic calculations of cooling stack of Manezh Central Exhibition Hall

After fire at Manezh Central Exhibition Hall, its ventilation system was seriously redesigned. As a part of this redesign, a free-standing underground cooling stack was installed to ensure air circulation in the ventilation system. For free outflow of air from the cooling stack, there is a bent corridor closed with a metal grid. For additional protection of the ventilation, it was decided to equip the outlet with a complicated air grid system. Therefore, Hexa Company set the problem to study an effect of additional air grid system for airflow movement in the underground room of the cooling stack.

Initial room geometry

Room geometry with additional air grids

  • Determine pressure in the outlet of the cooling stack required to ensure air flow through a complicated air grid structure.

  • Offer possible technical solutions for stabilization of airflow and reduction of pressure required for venting.

A cooling stack room was modeled to perform two-dimensional and three-dimensional analysis. In addition, during the work the models for several variants of changed room geometry were developed.

A fragment of solid finite element model

More than a million HEXA elements were used in the solid model.
Two-dimensional models contain about 50,000 elements.

Picture of airflow rate together with current lines in the air room of the cooling stack

The calculations confirmed concerns of the customer that installation of additional air grids considerably increased air pressure required for room venting. Therefore, there was a higher load on fans of the cooling stack and the risk of its damage. A figure below shows the comparison of pressure distribution in the cooling stack room. According to the calculations, there was 200% increase in pressure.

Initial room geometry

Room geometry with additional air grids

As a result of these calculations, several variants of change to the structure were proposed that would make it possible to reduce airflow resistance in the cooling stack room.

The cheapest and the most effective variant of redesign was selected. It was offered to use the so-called flow stabilizer in the room.

The comparison of pressure distribution in the cooling stack room is shown below. It is seen from the left figure that there is a non-uniform airflow distribution in the area of the air grid. Two of seven air grid outlets are virtually not used. In the structure with the stabilizer, seven outlets are used more uniformly.

Room geometry before redesign

Room geometry
with airflow stabilizer

The use of additional stabilizer reduces pressure required for venting by 16.3%.

Hexa Company to order of MOSPROJECT-2 named after M.V. Posokhin, 2005.

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