Wright State University Fall 2016

Department of Mechanical and Materials Engineering

ME 3320/5320: THERMODYNAMICS 2

FINAL EXAM 2

OPEN BOOK, CLOSED NOTES

Problem 1 (15 points): A gaseous fuel mixture that is 40 percent propane (C3H8) and 60 percent methane

(CH4) by volume is mixed with the theoretical amount of dry air and burned in a steady-flow, constant pressure

process at 100 kPa. Both the fuel and the air enter the combustion chamber at 298 K and undergo a complete

combustion process. The products leave the combustion chamber at 423 K. The H2O in the products is in the

vapor state. Determine the required air flow rate when the combustion process produces a heat transfer output

of 140,000 kJ/hr.

Problem 2 (15 points): The supersonic inlet contains an oblique shock wave followed by a normal shock wave.

For the conditions shown, find the stagnation temperature, the stagnation pressure, and the Mach number

behind the normal shock wave (Region 3). The working fluid is argon.

Problem 2, Thermo 2, Final Exam, Fall 2016 Oblique Shock equation: Find beta where function = 0

clc

clear all

close all

k = 1.667% ratio of specific heats

Ma1 = 3

theta = 18% degrees

beta = linspace(10,90,1000);

fcn = @(beta) (2*cotd(beta).*(Ma1^2*(sind(beta)).^2 - 1))./(Ma1^2*(k + cosd(2*beta)) + 2) - tand(theta);

z = fcn(beta);

beta_weak = fzero(fcn,50)

beta_strong = fzero(fcn,75)

plot(beta,z)

xlabel('Oblique Shock Angle, \beta (degrees)'), ylabel('Oblique Shock Equation')

grid on

title('Problem 2, Thermo 2, Final Exam, Fall 2016')

k =

1.6670

Ma1 =

3

theta =

18

beta_weak =

38.2232

beta_strong =

79.7711

Published with MATLAB® R2012b