CI engines operates in lambda>1 conditions for most of the time. So introducing a bit more air into combustion chamber shouldn't change operating conditions (except exhaust emissions). The same should happened if You introduce less air into combustion chamber. Of course it depends the quantity of air You are thinking. 

There is seem no simple relatonship. If the engine speed is kept constant, then an increase in airflow means an increase in engine inlet air density, resulting a higher torque outplut. A turbo is required to achieve this..  

For a naturally aspirated CI engine running at constant speed the mass of air flow will not change if the outside ambient temperature is steady even if fuel consumption is increased in order to achieve a high load. If you are interested in changing the air mass flow you need either to supercharge or turbocharge the engine at that constant speed.

If you have constant engine speed, and increase the load( eg going up hill)  the airflow would be greater than if you had the same constant speed on a flat road

thanks for your reply. I have turbocharger in the system.  I was doing some experiment. according to the experiment, for constant engine speed as i increase the load the mass flow in the system starts to decrease. the mass flow sensor is placed before the turbocharger., I am just wondering if these results are right ?

But at the same time the boost increases, the rpms would also start to rise 

@Sree ...

OK, if you have a turbo charger, the air mass flow will depend partly on the load. Though this will be a 'difficult' relation: you have to consider that at lowest loads the turbo may or may not add to an increase of air mass (as compared to a 'naturally aspired' engine) while at high loads the intake pressure will be limited by some kind of blowby valve.

Regarding an eventual increase of RPMs: this will not happen if there is some 'reasonable motor control electronics'. Such effects are easy to compensate.

Regards

Dear Sree nirjhor Kaysthagir in what units, does Your aparatus operates (dm3/h or kg/h). I work on turbocharged CRDI engine and during tests under constant speed while increasing torque I always get greater air consumption values. (My aparatus operates in kg/h units.) Try also to measure the temerature of intake air as along with greater degree of tubocharging the the temperature of intake air rises. Hotter air is less dense so it may be the clue of your question.