foo9008 said:
Yes, but from the text leading up to it I would say it was not just a slip of the pen. The author really does think it reaches a maximum there.SteamKing said:
so , it is true that the friction factor will increase when the flow become fully turbulent ? so , the author 's statement that the friction factor will become maximum is wrong ? hwo about the pumping power?haruspex said:
While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.haruspex said:
No.foo9008 said:
Yes.foo9008 said:
No. Read my Post #8 above and look at the Moody diagram.foo9008 said:
Yes, obviously.
The pumping power is still directly proportional to the pressure drop and the flow rate.
No, it operates against the author. The total friction increases as the velocity increases, but the friction factor decreases.SteamKing said:
SteamKing said:While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.
The Moody diagram, which plots friction factor versus Reynold's No., and by extension flow velocity, shows that the friction factor assumes a constant value which is independent of the Reynold's No. of the flow and hence the flow velocity for fully turbulent flow. That's what all those horizontal lines indicate on this diagram:
For a given value of relative pipe roughness, the friction factor takes on a relative maximum value somewhere in the transition zone between fully laminar and fully turbulent flow. Granted, the Reynold's No. at which the different types of flow appear seems to be somewhat arbitrary, having a minimum friction factor in the turbulent zone is quite obvious from the Moody diagram.
so , correct statement should be , the total friction become maximum ,while the frictional factor become minimum ?SteamKing said:While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.
The Moody diagram, which plots friction factor versus Reynold's No., and by extension flow velocity, shows that the friction factor assumes a constant value which is independent of the Reynold's No. of the flow and hence the flow velocity for fully turbulent flow. That's what all those horizontal lines indicate on this diagram:
For a given value of relative pipe roughness, the friction factor takes on a relative maximum value somewhere in the transition zone between fully laminar and fully turbulent flow. Granted, the Reynold's No. at which the different types of flow appear seems to be somewhat arbitrary, having a minimum friction factor in the turbulent zone is quite obvious from the Moody diagram.
Yes.foo9008 said:
so , beside the friction factor that cause the friction force , there are other fricition forces acting on it ?haruspex said:
You'll have to be more specific.foo9008 said:
what do you mean ?SteamKing said:
The pressure drop formula is:foo9008 said:
foo9008 said:
on fluid and pipeSteamKing said:
Doesn't seem to be for simple incompressible flows.foo9008 said:
No. The friction force is a product of various terms. One of them is the friction factor. As the flow velocity increases, the friction factor reduces a bit, but the other factors increase more, so the friction force overall increases.foo9008 said:
The friction factor at turbulent region, also known as the Darcy-Weisbach friction factor, is a dimensionless term used to quantify the resistance to fluid flow in a turbulent regime. It takes into account the surface roughness, fluid properties, and flow velocity to determine the amount of energy lost due to friction in a pipe or channel.
The friction factor at turbulent region is typically calculated using the Colebrook equation, which is an empirical formula that takes into account the relative roughness of the pipe and the Reynolds number. The equation is:
f = (-2.0 * log10((e/D)/3.7 + (12/Re*sqrt(f))))^-2
The friction factor at turbulent region can vary depending on the flow conditions and pipe characteristics, but it typically falls between 0.02 and 0.04. However, for very rough pipes, the friction factor can be as high as 0.1.
The roughness of a pipe has a significant impact on the friction factor at turbulent region. As the roughness increases, the friction factor also increases due to the increased surface area for fluid to interact with. This results in higher energy losses and a higher friction factor.
The friction factor at turbulent region is important because it allows engineers and scientists to accurately predict the energy losses in a pipe or channel due to fluid flow. This information is crucial in designing efficient and cost-effective systems for fluid transport in various industries, including oil and gas, water distribution, and HVAC systems.
