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Concert Hall HVAC

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Applications

      • Heating & Ventilation (HVAC)

Capabilities

  • Unsteady Reynolds Averaged Navier Stokes (URANS)
  • Buoyant Flow
  • Turbulence

Objective

Simulating the performance of a Displacement Ventilation System in a large open concert hall space. The problem tests the ability to model turbulent mixing and thermal buoyancy in a large space with complex geometry.

Case Description

The computational model of the building is based on the Calouste Gubenkian Foundation Concert Hall in Lisbon Portugal as reported by  Mateus et. al [1]. The hall has a total seating capacity of 1300 plus up to 250 performers. The HVAC system employed is of the Displacement Ventilation (DV) type where fresh air is introduced through the floor and removed through the ceiling. The DV approach offers advantages for large spaces with high ceilings over traditional ventilation systems that add fresh air near the ceiling to promote mixing. The advantages of a DV system are the elimination of regions of high C02, reduced ventilation velocity and noise, and reduced energy consumption. Design of a DV system requires advanced computational simulation to ensure that the occupants are not exposed to uncomfortable temperatures and drafts. The geometry used in the simulation is a mock up of the experimental setup of concert hall by Mateus et. al [1].

Reference Images

Concert HVAC[1].png

Fig. 1 Geometry of the concert hall showing the 3 regions: stage to the left, audience seating and balcony at the upper right.

Results

The figure below shows the time averaged temperature distribution and flow streamlines on a vertical central plane through the concert hall. The air is introduced at a velocity of 0.07 m/s through the floor of the 3 regions at a temperature of 19oC and removed through the ceiling. The audience and seating is modelled as a rough surface at 37oC (providing a significant heat load) and the wall surfaces are modelled as smooth surfaces at 20oC.  The mass flow rate is specified at six of the seven outflow boundaries to be equal with the seventh having a fixed reference pressure (over the stage). These mass flowrates can be adjusted to achieve the best air current distribution in the space. In practise this corresponds to pressure balancing the outlets. In the current configuration, the simulation results show the air currents that make their way from the inlets to the various outlets on the ceiling. These air currents are bordered by recirculation zones with increased air temperature. Buoyant action has a significant effect on the flow patterns and pressures of outlets located at different elevations. 

 

concerthall2..png

 Fig. 3 Time averaged temperature distribution and flow streamlines on a vertical central plane through the concert hall.

Simulation Outcomes, Timing, and External Factors

 

 Table 1 - Simulation performance outcomes

Reporting Item

EXN/Aero

Mesh Topology 

Multi-block unstructured

Data Type

Unstructured

Total Control Volumes

1.4 Million

Precision

Single Precision

GPU Type

Nvidia K20

GPU Number

4

GPU Memory

674 MiB

CPU Type

Intel Xeon

CPU Number 4
Delta Time 0.1 seconds
Total Simulation Time 1000 seconds
Total Compute Cost  22 hr * $13.3/hr = $292.60 

 

Notes

      The simulation was performed with unsteady RANS with SST turbulence model. Time averaged velocity and temperature are shown in the results.

Keywords

    • HVAC
    • SST-RANS
    • Incompressible
    • Unsteady

References

        [1] Mateus N. M., Graça G.C.da., "Simulated and measured performance of displacement ventilation systems in large rooms"
 
2018-02-12 | Categories: CFD

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