Question: Air at 1100°Cand 1013kPa pressure flows along a flat surface at a uniform velocity of 30 m/s. Investigate the problem of cooling this surface by transpiration cooling. At a point 1 m from the leading edge of the surface, consider the use of first air, then helium, as coolants, both of which are assumed to be available at 20°C. Prepare a plot of surface temperature as a function of coolant mass-flow rate per unit of surface area. Also calculate the surface temperature as a function of coolant mass-flow rate if the coolant were used merely to absorb heat rather than to pass into the boundary layer, assuming that the coolant leaves the system at surface temperature.