An experimental investigation was carried out to study the greenhouse adaptation, as a method, to
prevent separation at different values of Reynolds numbers in a sub-sonic two-dimensional flat‌walled diffuser.
The greenhouse implementation is attained by using a cotton screen, as impedance, of specific
porosity to slow down the hot air flow near the exit of the diffuser. The average velocity and
fluctuation fields have been measured with a constant temperature hot–wire anemometer
(CTA).However, in reversed flow zones pressures have been measured using 5-hole-probe.
The experimental measurements of velocity and pressure were made at six stations of the diffuser,
for different Reynolds numbers and specific value of porosity. The experimental results showed
that the greenhouse can be used to achieve separation delay, separation prevention, and pressure
recovery coefficient improvement in particular, for increasing Reynolds number. However, using
the greenhouse adaptation to prevent separation is not the only advantage but, the results show that
the diffuser is capable of giving a good performance and having a decreased boundary layer
thickness.