OldExam2ME525SP2008 - 1 Name_ ME 525 Exam #2 April 8, 2008...

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1 Name___________________________ April 8, 2008 Prof. Lucht ME 156 7:00-8:30 p.m. EXAM INSTRUCTIONS Write your name on each work sheet. At the end of the exam be sure to turn in all your work pages, and staple any extra work sheets to the work sheets provided. This exam is closed book and closed notes. When working the problem, list all assumptions, and begin with the basic equations. Problem #1 /30 Problem #2 /30 Problem #3 /30 Problem #4 /10 Total /100 ME 525 Exam #2
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2 ME 525 Exam #2 9 Apr 2007 Name___________________________ 1. (30 points) A detonation wave propagates in a tube closed at one end. The initial reactants are a mixture of H 2 and O 2 . The molar ratios for the reactant mixture are 8 kmols of H 2 to 1 kmol of O 2 . The reactant pressure is P 1 = 1 bar and temperature T 1 = 298 K. The measured temperature of the product gases is T 2 = 2650 K. Assume complete combustion and negligible dissociation. (a) Calculate the velocity u 1 (m/sec) of the unburned gases with respect to the detonation wave front, the velocity u 2 (m/sec) of the burned gases with respect to the detonation wave front, the final density 2 (kg/m 3 ), and the final pressure P 2 (bars) of the burned gases. (b) Check your answers to determine how well the momentum conservation and mass conservation equations are satisfied (it will be close but not perfect). 12 22 3 3520 2150 0.354 12.9 mm uu ss kg Pb a r s m 
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3 ME 525 Exam #2 9 Apr 2007 Name___________________________ 2. ( 30 points ) The table below lists flame properties calculated using the CHEMKIN PREMIX code for a burner-stabilized H 2 -air flame. The flame temperature (K) and the mole fractions of H 2 , O 2 , H 2 O, and N 2 are listed as a function of distance z (in cm) from the burner surface. The mole fractions of all other species in the flame gases total less than 1% and can be neglected in calculating MW mix . The pressure of 1 atm is uniform throughout the flowfield. Assume that the multi-component diffusion coefficient D i,mix for a species i in the mixture is approximately equal to the binary diffusion coefficient for species i and N 2 , D i,N2 . Use the Chapman-Enskog formula and the Lennard-Jones parameters, both given in the equation sheets, to calculate the binary diffusion coefficients. The atomic hydrogen (H) mole fraction profile and the polynomial fit to the data are shown in the plot on the next page.
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This note was uploaded on 12/27/2011 for the course ME 525 taught by Professor Lucth during the Fall '11 term at Purdue University-West Lafayette.

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OldExam2ME525SP2008 - 1 Name_ ME 525 Exam #2 April 8, 2008...

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