A fluid mixing apparatus and method in a fluid supply system that mixes a secondary fluid flow with a primary fluid flow in such a manner so as to minimize disruption of the fluid flow profile for the primary fluid flow downstream of the mixing point as the secondary fluid flow is introduced to the primary fluid flow. This is accomplished by providing a second conduit carrying the secondary fluid flow that is coupled to a first side of a first conduit carrying the primary fluid flow such that the secondary fluid flow travels around at least a portion of the first conduit. An inlet port arrangement is defined in the first conduit and is arranged such that a size of the inlet port arrangement that introduces the secondary gas flow from the second conduit into the first conduit increases as a distance around the first conduit from the first side increases.