MDE Unit 4 Q4

With reference to main engine turbo chargers, explain the purpose of EACH of the following:
(a) the volute casing;(3)
(b) the diffuser;(4)
(c) the nozzle ring.(3)

Volute Casing

Diffuser in a Main Engine Turbocharger

Nozzle Ring in a Main Engine Turbocharger