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Thermodynamics: An Engineering Approach, 4/e

Yunus A. Çengel, University of Nevada, Reno
Michael A. Boles, North Carolina State University

Thermodynamics of High-Speed Gas Flow

Multiple Choice Quiz

Answer all the questions


1	At one location in a nozzle, the air temperature is 400 K and the air velocity is 400 m/s. What is the stagnation enthalpy (based on temperature dependent specific heats) of the air at this location?
		A)	300 kJ/kg
		B)	357 kJ/kg
		C)	470 kJ/kg
		D)	481 kJ/kg


2	At one location in a nozzle, the air temperature is 400 K and the air velocity is 450 m/s. What is the Mach number at this location?
		A)	0.97
		B)	1.12
		C)	1.37
		D)	2.02


3	Air at 20 kPa flows with a Mach number of 1.5. What is the stagnation pressure of this air?
		A)	22.2 kPa
		B)	41.7 kPa
		C)	56.2 kPa
		D)	73.4 kPa


4	Air in a large tank at 350 K and 200 kPa is supplied to an isentropic converging-diverging nozzle. What is the temperature at a point in this nozzle where the Mach number is 1.2?
		A)	198 K
		B)	271 K
		C)	360 K
		D)	395 K


5	An isentropic, converging-diverging nozzle operates with stagnation conditions 400 kPa, 500 K. This nozzle has a throat area of 0.01 m² and is chocked. What is the mass flow rate through this nozzle?
		A)	5.01 kg/s
		B)	7.23 kg/s
		C)	8.32 kg/s
		D)	9.81 kg/s


6	The exit of the diverging section of an isentropic nozzle has twice the area of the nozzle throat. What is the Mach number at the exit when the exit flow is supersonic?
		A)	1.80
		B)	2.00
		C)	2.20
		D)	2.40


7	The exit of the diverging section of an isentropic nozzle has twice the area of the nozzle throat. If the stagnation pressure at the throat is 200 kPa, what is the pressure at the nozzle exit when the exit flow is supersonic?
		A)	18.7 kPa
		B)	32.2 kPa
		C)	87.3 kPa
		D)	137.2 kPa


8	An aircraft flies through 80 kPa, 270 K still air with a Mach number of 1.30. A normal shock wave will form directly in front of this aircraft. What is the stagnation pressure acting on this aircraft?
		A)	61 kPa
		B)	73 kPa
		C)	101 kPa
		D)	193 kPa


9	A normal shock wave forms in the diverging portion of a nozzle at a point where M_x = 1.5. The area at the exit of this nozzle is 50% larger then that where the shock wave forms. What is the Mach number at the nozzle exit?
		A)	1.2
		B)	1.12
		C)	0.38
		D)	0.24


10	Steam at 3.0 MPa, 500 °C, and negligible velocity is expanded to 0.8 MPa through an isentropic nozzle. What is the velocity of the steam at the nozzle exit?
		A)	268 m/s
		B)	522 m/s
		C)	738 m/s
		D)	894 m/s

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