wall 58 and towards first liner end 59 for cooling combustion liner 56 and for mixing with fuel from fuel nozzles 45 inside combustion liner 56 feed holes 55 are sized such that the pressure drop across the feed holes is minimized thereby supplying a higher air pressure to the cooling and combustion process than the prior art gas turbine combustor this is especially imperative when cooling a dual stage combustor that incorporates an effusion cooled combustion liner and a counter flow venturi similar to that shown in fig3 and disclosed in u s pat nos 6 427 446 6 446 438 and 6 484 509 assigned to the same assignee herein in this type of combustion system cooling air is drawn in to venturi cooling passageway 70 proximate venturi aft end 71 and is injected into a chamber 72 upstream of the venturi throat 73 for mixing with the fuel and air such that the fuel air mixture is leaner resulting in lower emissions when cooling a venturi in this manner the temperature of the cooling air rises dramatically while the air pressure drops as it passes through venturi cooling passageway 70 prior to being injected into chamber 72 flow throughout venturi cooling passageway 70 relies on pressure changes to pass the cooling air from venturi aft end 71 to chamber 72 therefore given the known pressure losses to occur in this system the air entering venturi cooling passageway 70 must initially.