Airfoil and a turbine apparatus

A turbine airfoil for relative movement in an ambient fluid, comprising:

• a main spar having a cross-sectional shape of an airfoil with a top side wall and a bottom side wall, a leading edge, a trailing edge, and a camber line extending from said leading edge to said trailing edge, wherein movement of said airfoil relative to said ambient fluid causes said ambient fluid to flow over said main spar in a downstream direction from said leading edge to said trailing edge, and
• discharge means operable to selectively discharge an evaporative fluid and a condensing fluid into said ambient fluid;
• wherein said main spar has a side wall extending from said leading edge to said trailing edge, said side wall having a first hill formation and a second hill formation, wherein both said first hill formation and said second hill formation include a first region of progressively increasing distance from said camber line, a second region of progressively decreasing distance from said camber line, and a crest at an interface between said first region and said second region, wherein said first region of said first hill formation is operable to interact with said ambient fluid to accelerate said ambient fluid from a high subsonic relative speed to a sonic relative speed over said crest of said first hill formation and a supersonic speed after said crest of said first hill formation;
• wherein said discharge means is operable to discharge said evaporative fluid to evaporate into said ambient fluid before condensation onset in said second region of said first hill formation, said second region of said first hill formation interacting with said ambient fluid to accelerate said ambient fluid from a supersonic relative speed to a higher supersonic relative speed;
• said first region of said second hill formation being operable to interact with said ambient fluid to decelerate and maintain said ambient fluid at said supersonic relative speed over said crest of said second hill formation, and
• wherein said discharge means is further operable to discharge said condensing fluid to nucleate condensation shock in said ambient fluid flowing over said second region of said second hill formation to decelerate said ambient fluid from said supersonic relative speed to said subsonic relative speed and generate a pressure on said side wall to impart thrust on said airfoil.