Basics of A Turboprop Engine P M V

Basics of A Turboprop Engine P M V Subbarao Professor Mechanical Engineering Department Enjoy the flying but pay for road travel ……

Economy Flying AN 12 : CRUISE SPEED : 520 km/h PAYLOAD : 18000 KG Range: 2400 km Maximum altitude: 7600 m

Requirements of Economic Flying • In recent years, interest in highly efficient flight transportation is renewed. • This has spurred investigation into very high bypass ratio fans. • Some economic optimization of turbofan cycle shows a bypass ratio of 100. • The weight of cowl and drag due to the cowl will have high penalty on total cost if bypass ratio is greater than 25. • This led to thinking of high bypass ratio open turbofan engines. • Turboprops.

Philosophy of Fuel Economy

Turboprop Engine : Just for Fuel Economy 3 1 1’ 2 p 02=p 01= p 03 = p 0∞ T 02=T 01 = T 03 = T 0∞ 4 5 6 p 04 =r 0 p, comp p 0∞ = p 05 T 04= =t 0 p, comp T 0∞ 7

Three Spool Turboprop Engine V U

Actuator disc theory for Propeller p. JD p p p. JU V U p 0 U 1 V D p 0 JD p 0 JU JU JD 1

Power Consumed by Propeller The ideal shaft power can be found using the integral energy equation on the control volume:

Shaft Power Balance for Turboprop Law of Turboprop

Propeller (Reaction) Power Propeller work coefficient: • The work coefficient of a propeller depends on compressor pressure ratio and turbine pressure ratio. • The compressor pressure ratio and turbine pressure ratio are two independent design variables for a turboprop.