WANTED: Formula for frictional resistance

Click For Summary
SUMMARY

The forum discussion centers on calculating the frictional resistance of a hydraulic lift using the formula Rf = 0.97 x Cf x Sw x V^2. The hydraulic lift features a 10.111-inch diameter ram within a 10.006-inch diameter cylinder, with oil having a kinematic viscosity of 0.0038 ft²/sec and a specific gravity of 0.83. The velocity of the ram is 0.5 ft/sec, and the user seeks clarification on whether the formula is applicable given that the fluid is oil rather than water. The constant 0.97 is specifically for fresh water, prompting the need for adjustments based on fluid properties.

PREREQUISITES
  • Understanding of hydraulic systems and their components
  • Knowledge of fluid mechanics, specifically kinematic viscosity
  • Familiarity with the concept of friction coefficients in fluid dynamics
  • Basic mathematical skills for evaluating expressions and formulas
NEXT STEPS
  • Research the effects of fluid type on frictional resistance calculations
  • Learn about the Coefficient of Friction (Cf) for different fluids
  • Explore the relationship between wetted surface area (Sw) and resistance in hydraulic systems
  • Investigate alternative formulas for calculating frictional resistance in non-water fluids
USEFUL FOR

Engineers, fluid mechanics students, and professionals involved in hydraulic system design and optimization will benefit from this discussion, particularly those focused on calculating frictional resistance in hydraulic lifts.

clueless
I do remember you folks to like to see where I left things. Well, let's change the arrangement. Give me formula and I will do the rest.

A hydraulics lift (type commonly used for greasing automobile) consist of a 10.111-in-diameter ram that slides in a 10.006-in-diameter cylinder. The annual space being filled with oil having a kinematic viscocity of 0.0038 ft^2/sec and specific gravity of 0.83. If the rate of travel of the ram v is 0.5fps, find the frictional resistance, F when 6ft of the ram is engaged in the cylinder...

I think this is simply evaluating expression problem once the expression is known to me. Am I underestimating the question?
 
Physics news on Phys.org
Is this what you are looking for?

Rf = 0.97 x Cf x Sw x V^2 where:

Rf = Resistance in pounds
Cf = Coefficient of friction
Sw = Wetted surface
V = Velocity in ft/sec
0.97 = Constant for fresh water

Source: http://www.greenval.com/shape_part1.html
 
I am not sure whether I have the formula I was looking for because the fluid in my problem is oil not the water. I will check out the website you were referring to. Thanks for your time and kindness.
 

Similar threads

Fluid problem -- Piston moving in an oil-filled cylinder
  • · Replies 9 ·
Replies
9
Views
6K