Incident heat flux

[nina-1-2]

Hello,
I want to measure an incident heat flux in the air. It is not possible on FDS6, I only can do it on a surface.
I tried 2 cases :

• Use the radiative heat flux gas with the following parameters :

Epsilon = 1
Ts = 0

• Use the gauge heat flux gas with the following parameters :

Epsilon gauge = 1
Tgauge = 0
Hc = 0

I isolated the incident heat flux from the formulas of the radiative heat flux gas and the gauge heat flux gas. However, when I measure it using these two quantities, I get different results.
Even by setting these parameters in order to isolate qinc, I was not able to find the same values for qinc. The differences in the results remain within the same order of magnitude.

As I was not able to find a guidance in FDS user guide, I was wondering if there are any additional parameters that FDS takes into account that I could set, or another method for measuring the incident heat flux ? Could you please give me some guidance on this ?

[drjfloyd]

The units for temperature in those equations is Kelvin and not Celsius. The units for the input in FDS is Celsius. To avoid re-radiation from the gauge you need to set it to 0 K not 0 C.