BAE 447 Midterm: BAE447 Exam 1 2017 Solution
31 Jan 2019
School
Department
Course
Professor
Name __________________
1 | Page
BAE 447
Midterm 1
This is an open book, closed notes exam. Everything you need to solve the problem is
either in your book or in the supplemental handout that was given to you with the exam
(or both).
If you believe you are missing a piece of information you need to solve a problem, please
ask.
Please write down all your steps, including units in all calculations.
You have 75 minutes to work the exam. I will collect the exams at 10:45 a.m.
The central part of the city of St. Paul, Minnesota is heated with hot water. A power
plant produces electricity from burning waste wood collected from the residential
areas. Waste heat, produced during the process of generating electricity, is transferred
to water that circulates through the downtown. A 4073 Kilowatt pump (80%
efficient) is used to move the water out of the city at 2.55
through a 0.61 m diameter
galvanized iron pipe.
Name __________________
2 | Page
(20) 1. A) Calculate the Reynolds number for the water leaving the pump house. The
water has been heated to 49 °C.
so we need to find V
At 49 °C, ρH2O=987
,5.5810 (page 20, Table 2-1 in book)
Apipe =
.
0.292
V =
.
. = 8.73
=
..
. =
..
.
= 9,422,586 = 9.4 x 106
B) Calculate the friction factor f.
ϵ for galvanized iron pipe = 1.5 x 10-4 m, so
.
. 0.000245
f from Moody’s diagram = 0.0145
Document Summary
This is an open book, closed notes exam. Everything you need to solve the problem is either in your book or in the supplemental handout that was given to you with the exam (or both). If you believe you are missing a piece of information you need to solve a problem, please ask. Please write down all your steps, including units in all calculations. You have 75 minutes to work the exam. I will collect the exams at 10:45 a. m. The central part of the city of st. paul, minnesota is heated with hot water. A power plant produces electricity from burning waste wood collected from the residential areas. Waste heat, produced during the process of generating electricity, is transferred to water that circulates through the downtown. A 4073 kilowatt pump (80% efficient) is used to move the water out of the city at 2. 55 (cid:3040)(cid:3119)(cid:3046) through a 0. 61 m diameter galvanized iron pipe.
