Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations SDETERS on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Orifice flow, temperature/viscous effects

Status
Not open for further replies.

lfw618

Mechanical
Oct 4, 2018
61
I have a general question on flow through an orifice for varying temperatures/viscosities. For a given pressure drop and orifice size, intuitively I would expect a colder, more viscous oil to have less flow through the orifice than oil at temp. However from looking at the Reader-Harris/Gallagher equation for discharge coefficient, the coefficient of discharge is inversely related to the Reynolds number. Since Reynolds number is inversely related to to fluid viscosity, this would suggest to me that a more viscous fluid will have a higher discharge coefficient, resulting in more flow through an orifice for a given pressure drop relative to the less viscous fluid at temp. Which does not seem intuitive to me. Is this correct or can someone help point me to what I'm missing here? Thanks in advance.
 
Replies continue below

Recommended for you

Hello,
If that can help you:
For hydraulic oil of density 0.932 in a thin-walled nozzle the flow rate is = 0.5 ø² (dP) ^ 0.5. For a low pressure or a high viscosity I multiply the flow rate by a coefficient V.
If necessary I have the formula of the coefficient V for calculation on a computer
cordially
 
 https://files.engineering.com/getfile.aspx?folder=422b951b-ebd8-4b48-b251-32b1641cc496&file=correct_débit_gicleur_f(visc+dP).pdf
Status
Not open for further replies.

Part and Inventory Search

Sponsor