The forward opening is the forward outflow valve or forward overboard valve (depending on reference consulted) which opens automatically if airflow in the forward compartment is low. It is independent from the two large aft outflow valves at the lower aft hull used for pressurization.
The second valve is the smoke override valve used in case there is smoke sensed in the the E&E compartment. Basically you try to get rid of the smoke by dumping it overboard. The second function is in case the fans used for ventilation of the E&E compartment fail. Then this valve is opened as well and the differential pressure ventilates the E&E compartment in reverse flow direction. The duct who was supplying the air is now sucking it out of the compartment.
The opening close to the pack inlet on the R/H side is the ground exhaust valve used to dump the air used for E&E cooling on ground overboard in case the temperature is high. This valve is always closed in flight.
- Boeing 747-400 System Schematic Manual, chapter 21, valves V462 (forward overboard valve), V447 (ground exhaust valve), V448 (smoke override valve)
- internal documentation provided by employer of the author