PSI - Issue 73

Juraj Králik et al. / Procedia Structural Integrity 73 (2025) 73–80 Juraj Králik/ Structural Integrity Procedia 00 (2025) 000–000

79 7

v ref z ref z o z o κ ⋅ +

35.64 0.4 ×

*

1

−

2.688 .

.

(4)

v

ms

=

=

=

   

ln     

  

10 0.05 +

ln

 

0.05

The relative turbulent dissipation profile is considered in the form:

*3

v

( ) z

.

(5)

ε

=

(

)

z z

⋅ +

κ

0

The relative profile of specific turbulent dissipation is of the form:

( ) z

ε

( ) z

,

(6)

ω

=

k

where k is the kinetic energy of turbulence, defined in the form:

*2

2

2.688

v

2 2 −

24.087

k

m s

,

(7)

= =

=

0.09

C µ

where C μ = 0.09 is the model constant. All simulation results were processed in the CFD-Post module. The main task of these simulations was to determine the external pressure coefficients at the NPP. Individual results are compiled for each of the perpendicular directions of extreme air flow around the NPP objects. The results in the following chapters come from the Standard k - ω model. The external pressure coefficients were calculated according to:

p p −

0

,

(8)

c

=

,10

pe

2 1 2. . v ρ

where p is the pressure on the surface, p o is the reference static pressure at the reference point at the "INLET" at the height of the highest edge of the building, ρ is the air density, v is the air velocity at the "INLET" inlet at the reference height. 3.2. Analysis of the wind load on the ventilation chimney In the chimney analysis, the turbulent SST k - ω model clearly provided better results, which is also more suitable for analyses with high pressure gradients (Kawoluk, 2023, Menter, 2020, Králik, 2020, 2022). At the upper level of the chimney (125m), the reference velocity v b = 53.8m/s, which also corresponds to high pressures. The wind pressure on the chimney was defined by eq. (2). The wind loads based on c pe factors determined in the Tab.2 and the base wind velocity were applied on the FE model of the chimney for following safety analysis Králik (2022) in software ANSYS.

Table 3. Comparison of the experimental and numerical analysis of the c pe factors on ventilation chimney with standard. Wind impact Methods Vertical level of section [ m ] Direction Wall 27.60 53.7 81.3 113.4 South Windward Experiment 0.05 0.64 1.14 1.37 Fluent 0.30 0.59 0.77 0.90 Eurocode 1.0