Previous in Forum: Generator - Alarms of a Deutz E11.4 Genset   Next in Forum: Multi Split Unit vs. Variable Refrigerant Flow Unit
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
Rate Comments: Nested
Aussie Ray
Member

Join Date: Apr 2008
Posts: 7

Shear Rate Calculation

08/13/2010 4:56 AM

Hi CR4 Readers,

I wish to calculate the shear rate of an agitator impeller with the units of 'per second' (s-1). Please advise a formula for this. The hydrofoil impeller is 1.76m diameter an running at 70rpm. I believe the answer should be around 4 s-1 .

There also appears to be another shear rate expressed in units of m/s. The formula is T = pi x D x N/60.

Thanks for your help.
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Codemaster
Guru

Join Date: Jul 2005
Location: Stoke-on-Trent, UK
Posts: 4496
Good Answers: 137
#1

Re: Shear Rate Calculation

08/13/2010 6:26 AM

Formula is √(W/V/μ) where W = power, V= volume, μ = dynamic viscosity. All in consistent units of course. You can work it out from first principles assuming laminar flow.

4 s-1 seems very low, even for say a flocculation stage on water treatment. Estimating your tank volume at 10 m3 and assuming viscosity as water (1 cP), I make that only 0.2 watt (into the water) to give 4.5 s-1 .

Don't know about the other shear rate.

Cheers.......Codey

__________________
 Give masochists a fair crack of the whip
Register to Reply
Register to Reply
Have a Different Question?

Previous in Forum: Generator - Alarms of a Deutz E11.4 Genset   Next in Forum: Multi Split Unit vs. Variable Refrigerant Flow Unit
You might be interested in: Centrifugal Pumps, Bit Error Rate Testers, Impellers

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Mechanical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (60 right now)
Show Members
Advertisement