Question: only answer problem 5 please problem 4 is there for...
Only answer problem (5), please. Problem (4) is there for reference, as you will see is necessary in problem (5). Thank you.
4. Consider the flow from a gas turbine combustor, into a turbine which produces work and then into a nozzle for producing thrust. The flow in the turbine is modeled as isentropic even though work is done. The turbine consists of a nozzle to accelerate the flow toward the turbine blades followed by the rotating turbine and then a diffuser in most cases. If the flow conditions in the combustor are essentially stagnant at 1500K and 10 atm, a converging-diverging nozzle accelerates the flow to Mach 1.5 just in front of the turbine blades, and the total conditions just downstream of the turbine are near stagnant with a total pressure of 5 atm .
5. Consider a nozzle similar to that of problem 4: A nozzle accelerates a flow with stagnation conditions of 45 psia and 540R isentropically to Mach 2. Subsequently, the flow goes through a diffuser, encountering an oblique shock train before regaining a stagnation condition of 30 psia and 540R. If the flow is choked again isentropically, what is the ratio of the throat area for the second choke point to the throat area for the first choke point? How much entropy per unit mass was added in the shock train? Is this entropy increase due to an interaction or irreversibilities?