The present invention includes a gas turbine engine exhaust centerbody comprising a forward portion having at least one flap at a downstream end thereof to induce a local low pressure zone in the exhaust gas flow without significantly impeding it, a tailcone partially inserted into the forward portion so that at least part of the at least one flap overlaps a portion of the tailcone, a centerbody cavity containing gas at a pressure higher than the local low pressure, and at least one opening between the forward portion and the tailcone adjacent to and upstream of one of the local low pressure zones and providing fluid communication between the cavity and the exhaust gas flow. A ventilation flow out of the centerbody cavity through each opening is induced by a positive difference between the pressure of the gas in the centerbody cavity and the low pressure of the adjacent zone.