What is the fuel/air ratio of the CFM56-5A1 engine (in the A320 model)?
The ratio can be different for different phases of flight. It is easy to calculate for the Takeoff (TO) case because the required numbers are easily available:


TO Thrust: $ 25 \, 000 \, \text{lbs} $ [1]
TO TSFC (thrust specific fuel consumption): $ 0.3316 \, \text{lbs/h} $ per $ 1 \, \text{lbs} $ of thrust [2]
Airflow: $ 852 \, \text{lbs/h} $ [1]
bypass ratio: $ 6.0 : 1.0 $ [1]


The takeoff fuel flow $ \text{FF} $ is then given by

$$ \text{FF} = 25 \, 000 \times 0.3316 \, \text{lbs/h} \approx 8290 \, \text{lbs/h} \approx 2.30 \, \text{lbs/s} \approx 1.04 \, \text{kg/s} $$

and the airflow $ \text{AF} $ through the core is given by

$$ \text{AF} = \frac{1}{6 + 1} \times 852 \, \text{lbs/s} \approx 122 \, \text{lbs/s} \approx 55.2 \, \text{kg/s} $$

This results in a fuel/air ratio of

$$ \frac{\text{FF}}{\text{AF}} \approx \frac{1}{52.9} \approx 0.0189 $$

Sources:


[1]: www.cfm56.com
[2]: Wikipedia CFM56