) An axial flow turbine operating with an overall stagnation pressure of 8 to 1 has a polytropic

efficiency of 0.85. Determine the total-to-total efficiency of the turbine.

(ii) If the exhaust Mach number of the turbine is 0.3, determine the total-to-static efficiency.

(iii) If, in addition, the exhaust velocity of the turbine is 160 m/s, determine the inlet total

temperature.

Assume for the gas that CP 1.175 kJ/(kg K) and R 0.287 kJ/(kg K).

3. The mean blade radii of the rotor of a mixed flow turbine are 0.3 m at inlet and 0.1 m at outlet.

The rotor rotates at 20,000 rev/min and the turbine is required to produce 430 kW. The flow

velocity at nozzle exit is 700 m/s and the flow direction is at 70 to the meridional plane. Determine the absolute and relative flow angles and the absolute exit velocity if the gas flow is 1 kg/s

and the velocity of the through-flow is constant through the rotor.

4. In a Parson's reaction turbine the rotor blades are similar to the stator blades but with the angles

measured in the opposite direction. The efflux angle relative to each row of blades is 70 from

the axial direction, the exit velocity of steam from the stator blades is 160m/s, the blade speed is

152.5 m/s, and the axial velocity is constant. Determine the specific work done by the steam per

stage. A turbine of 80% internal efficiency consists of 10 such stages as just described and

receives steam from the stop valve at 1.5 MPa and 300C. Determine, with the aid of a Mollier

chart, the condition of the steam at outlet from the last stage.

5. Values of pressure (kPa) measured at various stations of a zero reaction gas turbine stage, all at

the mean blade height, are shown in the table that follows:

Stagnation pressure Static pressure

Nozzle entry 414 Nozzle exit 207

Nozzle exit 400 Rotor exit 200

The mean blade speed is 291 m/s, inlet stagnation temperature 1100 K, and the flow angle at

nozzle exit is 70 measured from the axial direction. Assuming the magnitude and direction

of the velocities at entry and exit of the stage are the same, determine the total-to-total efficiency

of the stage. Assume a perfect gas with Cp 1.148 kJ/(kg C) and ? 1.333.

6. In a certain axial flow turbine stage the axial velocity cx is constant. The absolute velocities entering and leaving the stage are in the axial direction. If the flow coefficient cx /U is 0.6 and the gas

leaves the stator blades at 68.2 from the axial direction, calculate

(i) the stage loading factor, ?W/U2

;

(ii) the flow angles relative to the rotor blades;

(iii) the degree of reaction;

(iv) the total-to-total and total-to-static efficiencies.

The Soderberg loss correlation, eqn. (3.50) should be used.

1. The first law of thermodynamics and the conservation of energy, as discussed in Conservation of Energy, are clearly related. How do they differ in the types of energy considered? 2. Heat transfer QQ and work done WW are always energy in transit, whereas internal energy UU is energy stored in a system. Give an example of each type of energy, and state specifically how it is either in transit or resides in a system. 3. How do heat transfer and internal energy differ? In particular, which can be stored as such in a system and which cannot?4. For computer chip of 25 mm (length), 9 mm(width) is operated by power of 0.645 Watt, which surrounded by coolant material of temp of 85 F. Find the Surface Temperature in F of the computer chip during the heat transfer of convection. The Internal energy is 5.5 J/sec, KE=6.9 J/sec, and PE-3.5 watt (Hints: heat convection, Q= - hAdT, heat transfer coefficient, h=150W/sq.m K , W=J/sec, Apply 1" law of thermodynamics) 5. A system of known mass (4kg) is located at the height of 1000m to a process for the work (100 kJ) and heat transfer (25 kJ) and the specific internal energy change (25 kJ/kg). Find the Change in Kinetic Energy in kJ (Hint, use ]" Law of thermodynamics).4) Mechanical power at the output of rotational shaft is given as: P = WT Where: W=100 rad/s + 2% is the angular speed. T=20 +1 N.m is the rotational torque. Calculate the mechanical power of rotational shaft and its percentage uncertainty using analytical and numerical methods. 5) The angular velocity of DC motor is given as: W= U-IR C Where: U =220V + 1% is the input voltage, I= 10A+2%, is the armature current, R=4+0.20 is the resistance of armature circuit, and the magnetic field density C=1.4+ 0.1 VS/rad. Calculate the angular velocity of motor and its percentage uncertainty using analytical and numerical methods.a) A stationary closed system goes through a process from state 1 to state 2 and returns from state 2 to state 1 as shown in Figure Q1a. Write the First Law of Thermodynamics or energy balance equation for the system as it goes through process 1-2. ii. The change in internal energy for process 1-#2 is 60 J. The work done on the system for the return process 2-#1 is 30 J. What is the amount of heat transferred for this return process 2- 1? Is heat released from the system or is heat received by the system during the return process 2-1? P (Pressure) 1 V (Volume) Figure Q1a