School of Aerospace Engineering
Thermal Science (18AS41) – Batch 2019
Unit II
Assignment 2 (50 marks)
1. Air with a mass flow rate of 2.3 kg/s enters a horizontal nozzle operating at steady state
at 450 K, 350 kPa, and velocity of 3 m/s. At the exit, the temperature is 300 K and the
velocity is 460 m/s. Using the ideal gas model for air with constant cp = 1.011 kJ/kg K,
determine (a) the area at the inlet, in m2, (b) the heat transfer between the nozzle at its
surroundings, in kW. Specify whether the heat transfer is to or from the air.
2. Air modeled as an ideal gas enters a well-insulated diffuser operating at steady state at
270 K with a velocity of 180 m/s and exits with a velocity of 48.4 m/s. For negligible
potential energy effects, determine the exit temperature, in K.
3. Water is pumped from a lower reservoir to a higher reservoir by a pump that provides
20 kW of shaft power. The free surface of the upper reservoir is 45 m higher than that
of the lower reservoir. If the flow rate of water is measured to be 0.03 m3/s, determine
mechanical power that is converted to thermal energy during this process due to
frictional effects.
4. A student living in a 3-m x 4-m x 4-m dormitory room turns on her 100-W fan before
she leaves the room on a summer day, hoping that the room will be cooler when she
comes back in the evening. Assuming all the doors and windows are tightly closed and
disregarding any heat transfer through the walls and the windows, determine the
temperature in the room when she comes back 8 h later. Use specific heat values at
room temperature, and assume the room to be at 100 kPa and 20oC in the morning when
she leaves.
5. The diffuser in a jet engine is designed to decrease the kinetic energy of the air entering
the engine compressor without any work or heat interactions. Calculate the velocity at
the exit of a diffuser when air at 100 kPa and 30oC enters it with a velocity of 350 m/s
and the exit state is 200 kPa and 90oC.
Instructions
1. Please complete the assignment before 29th March 2021, 12:00 PM.
2. Use atmospheric data tables wherever applicable.
Thermal Science (18AS41) – Batch 2019
Unit II
Assignment 2 (50 marks)
1. Air with a mass flow rate of 2.3 kg/s enters a horizontal nozzle operating at steady state
at 450 K, 350 kPa, and velocity of 3 m/s. At the exit, the temperature is 300 K and the
velocity is 460 m/s. Using the ideal gas model for air with constant cp = 1.011 kJ/kg K,
determine (a) the area at the inlet, in m2, (b) the heat transfer between the nozzle at its
surroundings, in kW. Specify whether the heat transfer is to or from the air.
2. Air modeled as an ideal gas enters a well-insulated diffuser operating at steady state at
270 K with a velocity of 180 m/s and exits with a velocity of 48.4 m/s. For negligible
potential energy effects, determine the exit temperature, in K.
3. Water is pumped from a lower reservoir to a higher reservoir by a pump that provides
20 kW of shaft power. The free surface of the upper reservoir is 45 m higher than that
of the lower reservoir. If the flow rate of water is measured to be 0.03 m3/s, determine
mechanical power that is converted to thermal energy during this process due to
frictional effects.
4. A student living in a 3-m x 4-m x 4-m dormitory room turns on her 100-W fan before
she leaves the room on a summer day, hoping that the room will be cooler when she
comes back in the evening. Assuming all the doors and windows are tightly closed and
disregarding any heat transfer through the walls and the windows, determine the
temperature in the room when she comes back 8 h later. Use specific heat values at
room temperature, and assume the room to be at 100 kPa and 20oC in the morning when
she leaves.
5. The diffuser in a jet engine is designed to decrease the kinetic energy of the air entering
the engine compressor without any work or heat interactions. Calculate the velocity at
the exit of a diffuser when air at 100 kPa and 30oC enters it with a velocity of 350 m/s
and the exit state is 200 kPa and 90oC.
Instructions
1. Please complete the assignment before 29th March 2021, 12:00 PM.
2. Use atmospheric data tables wherever applicable.
