# Hydraulic Machines and Compressible Flow - Need time saving advice



## abourne (Sep 21, 2010)

I probably spent over 15 hours on Chapter 17, Fluid Dynamics.

I'm taking Rich Davis's ME PE Review class and last week had Hydrualic Machines and Compressible Flow.

I need to catch up and do the homework for Chapter 18 - Hydraulic Machines and Chapter 26 - Compressible Flow.

In order to save time - just for these two chapers - I'm looking to do the core problems that are relevant to the exam.

Looking at Chapter 18, I'm considering problems:

Do: 1-4

Skipping 4-9, 17, 21 (the "one hour problems)

Please let me know which problems are important for:

- Specific Speed

- Cavitation

- Pumps and System Curves

- Affinity Laws

- Turbines

Also, if the class notes/example problems can be substituted for any of the above.

Also, please provide a summary for Chapter 26 - Compressible Flow, if I'm only going to do a few problems, which ones should I do.

Since I'm doing the Thermo for the afternoon portion of the the exam, I may have a couple of weeks to catch up.

Tonight, I have HVAC - 1, which I only need to attend the first hour - Pschometrics

and next week I have HVAC 2, which I only need a litte bit of info for Fans and Ducts, as it may pertain to Fluids.

I plan to take advantage of this upcoming two-week HVAC section to catch up on homework for the following:

* I've only done half of Economics - need to do the other half

* For Machine Design, I'm going to do a couple of Gear Ratio examples from Schigley and the example class problem - this should get me credit for Machine Design HW (since I'm a Thermo guy)

* I still need to do chapters 32 and 33 - Refrigeration Cycles - I completed all the other Thermo and Power Vapor systems problems

* Chapters 18 and 26, Hydraulic Machines and Compressible flow discussed above

Seems like the work never ends.

The next two sessions after HVAC are

* Heat Transfer

* Combustion

Then, I have maybe a couple of weeks to do the following:

* Review all the homework, materials, examples I've done since July

* MERM Practice Exam

* NCEES Practice Exam

* Six-minute Solutions

* Orgainize

Please provide tips on the basics for Chapters 18 and 26, or emphasize the minimum standards I need to know for the test.

Thanks in advance.


----------



## navyasw02 (Sep 21, 2010)

abourne said:


> I probably spent over 15 hours on Chapter 17, Fluid Dynamics.


15 hours on ONE chapter? Holy crap. I dont know how much familiarity you have with the material, but that seems to be an awful long time for one out of about 15-20 chapters of material. I personally would spend more time getting a broader knowledge base than worry about every minute detail in one chapter. Overall, you may really only have one or two questions on the test that directly use that material and it's way more important to know where to find things and roughly how to use the equations and concepts instead of being an expert on the fine points. Tabs and a highlighter will help.


----------



## abourne (Sep 21, 2010)

navyasw02 said:


> 15 hours on ONE chapter? Holy crap.


Fluid Dynamics, Chapter 17, is the "Monster Chapter".

This chapter is like no other, there are hundreds of forumlas, charts, tables, etc. to be familiar with. Many of the problems really aren't extremely difficult, but there's a lot of work to do here.

Rich described this as the "Monster Chapter".

So far, I've done:

Economics, Dynamics (23, 54-56, 58) Statics (43-36), Mechanics of Materials (48, 49), Failure Theorey (did this quickly as a thermo guy), skipped Machine Design, but will focus on gear ratios and basics. Also, Mohr's circle is important, Thermodynamics (24, 25, 27), Power Cycles (28, 29, 31-33, although I still need to do 32 and 33), Fluids (14-16 was quick, 17 was monster), and I'm currently behind on Hydrualic Machines and Compressible Flow (18 and 26).

I hear Heat Transfer is a lot of work (34-37) and then the following week is Combustion (21, 22).

The next two lessons are HVAC, so hopefully I'll be able to catch up these next two weeks before the Heat Transfer lecture on October 5th.

October 5th - Heat Transfer

October 12 - Combustion

October 19th - Review

Assuming I get all caught up on the homework and complete Combustion by October 15th, I'll have about two weeks to review before the test.


----------



## navyasw02 (Sep 21, 2010)

abourne said:


> navyasw02 said:
> 
> 
> > 15 hours on ONE chapter? Holy crap.
> ...


I'm out of town so I cant look at my book. What's 17 got? Is that the one with all the pump head and all that stuff with the 500 different roughness factors for pipe flow or is it the chapter that has the buoyancy stuff? Fluids for me as long as you're comfortable with bernoulli's equation will help you solve at least half of the problems in fluids. The other type of problem is finding temps/pressures etc across a nozzle or diffuser, but that's just really just a conservation problem. I doubt you'll have to go into detail on more advanced topics like stream functions and shocks, rayleigh and fanno flows, and things like that.

Heat transfer if you understand fluids is super simple. Just break it down into conduction, convection, and radiation. Conduction your main types of problems will probably involve calculating the heat flow through a solid or combined solids similar to adding resistors. The only trick is to make sure you know your start and end points ie, treat it differently if your start point is on the conductive surface instead of away from it. Convection as long as you know fluids is simply a matter of first calculating the Reynolds number before you do anything else, then figure out if its laminar or turbulent and then plug and chug using the right equation for the right conditions like flat plate or tubes or whatever. Fins are tricky though, but they're a special case. Also study heat xchangers separately which usually include doing some sort of LMTD calculation. Once you do one or two of those, they become second nature. Radiation is a turd, just study that and remember the relationship between emissivity and absorption.


----------



## abourne (Sep 22, 2010)

navyasw02 said:


> What's 17 got?


17 is everything you've mentioned plus the kitchen sink. Bernoulli, energy balance, laminar, turbulent, Re, Le, Darcy friction, major and minor losses, etc. All incompressible flow, constant density. Uses Appendix 14.A to find density at varying temps and kinematic viscosity, Re, pipe-roughness, Darcy friction, Hazen Williams (C always given if this is the case), tables to find D_inner, etc.

Pumps is more covered in Hydraulic Machines.


----------



## Baltimore Joe (Sep 22, 2010)

Please provide tips on the basics for Chapters 18 and 26, or emphasize the minimum standards I need to know for the test.


----------



## Shaggy (Sep 22, 2010)

post deleted (I misread your original post). Shoot an email to Rich, he will help you decide what to trim.


----------



## abourne (Sep 22, 2010)

Shaggy said:


> Shoot an email to Rich, he will help you decide what to trim.


I don't think I want to email Rich on that. He's talked quite a bit over the past ten weeks and he's pretty reluctant to telling people what they can skip. Once in a while, if you're not an afternoon person on a particular topic, you may be able to get something out of him, but the bottom line is, when I started this post, I was pretty overwhelmed.

Last night, Rich said part of this exam is managing your head.

Psychometrics, which I had last night a full three hours and I'm going to have to spend the equivalent amount of time on that too.

I may have to take some time off and study for this exam full-time, especially as the exam approaches. I'm just going to have to get into gear, do chapters 18, 26, 38 (HVAC Pshchometrics), 32, 33 (Refrigeration Cycles), Economics (second part), and follow-through with Combustion and Heat Transfer.


----------



## Shaggy (Sep 22, 2010)

I did the Machine Design afternoon, so I don't have any input on the Thermo/Fluids afternoon. Sorry. Initially I was thinking you were taking the MD afternoon as well.


----------



## abourne (Sep 26, 2010)

Turns out it was just anxiety afterall.

Last Thursday, I didn't go to work, went to the library, and completed Hydraulic Machine notes as well as Chapter 18 in MERM.

Friday, I read up on Incompressible Flow in another book, did the basic problems from class, and today, I completed all the homework problems (except the 1-hour problems) in Chapter 26.

Chapter 26 - Incompressible Flow, actually seems like one of the easiest chapters so far. I'm proud to say I completed problems 1-7 without looking at the solutions. It wasn't until No. 8 whereby an "assumption" had to be used (which I doubt will be on the exam).

I have thought about it and I think it's going to be best for me to take at least two weeks off of work prior to the exam.


----------



## heath014 (Sep 28, 2010)

What are you doing within these 15 hours on Chapter 17? When I began studying I spent WAY too much time trying to read and review the theory. Just do problems. If you are having issues with the problems go back and review the trouble areas in the book.


----------



## abourne (Sep 28, 2010)

As I've mentioned before, Chapter 17 is the monster chapter.

I do all the homework problems, as recommended by this class, and Fluid Dynamics problems are long and tedeous.

I never spent anywhere more than 1-3 hours on any other chapter's homework problems.

For the exam, homework and actual solved problems, are our best reference.

Oh, and by the way, the 15 hours was doing the problems. Well, maybe I've over-estimated it, but was certainly the most time-consuming chapter when it comes to completing the homework. Mostly tedeous.


----------

