The reference Noctua fan actually does that! It goes to show that Noctua actually has good engineers, and their fans prove this. Lo and behold the reference fan is the best standard fan, so you are on to something! The cheater fan that sits at the top has an inlet shroud and an exhaust shroud. You can have the fanciest nicest turbine engine in the world, but it's not a jet engine, it's just a turbine. The one little feature that makes a jet engine a jet, is, the nozzle at the exit. That converging section right at the end converts everything that happens in the turbine into a jet. Check out a fighter jet, like an F18, the jet nozzles converge and produce thrust, then the re-heat/afterburner kicks in and the exhaust flow goes supersonic, then the nozzle opens up and becomes divergent. Here's a thought, if a fan blade were to function like a fixed wing would it be as effective, or is the fan blade dependent on the yaw angle of the airflow? If the latter is true then it must also apply to a car that's turning correct?