About Rayleigh parameter

Hyun

Hi all.

As you know, Rayleigh criterion is a integration of unsteady pressure fluctuation and unsteady heat release wrote

Ra = integrate (p'* q')

p' means p'(x,t) = p(x,t) - p_mean, and it is calculated directly.

q' means unsteady heat release term.

how can I calculate q' term?

I have read following

q' = rho_u * dhr * vol

where rho_u : density of unburned gas dhr : heat of reaction vol : volume

I have calculated unsteady reacting flowfield and have information about species concentration, flow variables and thermodynamic variables.

How can I get the value of heat of reaction??

please give me advices.