Friction Losses Lab Report - Fluids
Friction Losses
Abstract—The purpose of the experiment is to study the differences of roughness, valves and geometries of pipe and how they influence friction losses.
Introduction
Friction loss is the loss of energy or “head” that occurs in pipe flow due to viscous effects generated by the surface of the pipe. This energy drop is dependent on the wall shear stress (τ) between the fluid and pipe surface. The shear stress of a flow is also dependent on whether the flow is turbulent or laminar. For turbulent flow, the pressure drop is dependent on the roughness of the surface, while in laminar flow, the roughness effects of the wall are negligible. This is due to the fact that in turbulent flow, a thin viscous layer is formed near the pipe surface which causes a loss in energy, while in laminar flow, this viscous layer is non-existent. Causes of friction loss can include the movement of fluid molecules against one another, or against the inside surface of the pipe and bends, kinks or sharp turns in hose or piping.
This experiment allows us to investigate different scenarios of piping, particularly in roughness, geometry and valves. With the many circuits of flow to chose from the student can combine different variations of each to see how the flow responds.
Governing Equations
Basic Head Loss for Strait Pipes
Head loss can be expressed as a function of friction factor: (eq 1)
Where hf is head loss, L is length, D is diameter of pipe, V is the velocity of the flow and g is gravity.
Flow Rate
The flow rate in a pipe can also be calculated using
(eq 2)
In this case u is used for velocity, Q as volume flow rate and A, cross sectional area of the pipe.
Reynold’s Number
In fluids, the Reynolds number (Re) is a dimensionless number which gives a measure of the ratio of inertial forces to viscous forces. The Reynold’s Number is also used to classify laminar and turbulent flow values. When working with pipes that have different
Abstract—The purpose of the experiment is to study the differences of roughness, valves and geometries of pipe and how they influence friction losses.
Introduction
Friction loss is the loss of energy or “head” that occurs in pipe flow due to viscous effects generated by the surface of the pipe. This energy drop is dependent on the wall shear stress (τ) between the fluid and pipe surface. The shear stress of a flow is also dependent on whether the flow is turbulent or laminar. For turbulent flow, the pressure drop is dependent on the roughness of the surface, while in laminar flow, the roughness effects of the wall are negligible. This is due to the fact that in turbulent flow, a thin viscous layer is formed near the pipe surface which causes a loss in energy, while in laminar flow, this viscous layer is non-existent. Causes of friction loss can include the movement of fluid molecules against one another, or against the inside surface of the pipe and bends, kinks or sharp turns in hose or piping.
This experiment allows us to investigate different scenarios of piping, particularly in roughness, geometry and valves. With the many circuits of flow to chose from the student can combine different variations of each to see how the flow responds.
Governing Equations
Basic Head Loss for Strait Pipes
Head loss can be expressed as a function of friction factor: (eq 1)
Where hf is head loss, L is length, D is diameter of pipe, V is the velocity of the flow and g is gravity.
Flow Rate
The flow rate in a pipe can also be calculated using
(eq 2)
In this case u is used for velocity, Q as volume flow rate and A, cross sectional area of the pipe.
Reynold’s Number
In fluids, the Reynolds number (Re) is a dimensionless number which gives a measure of the ratio of inertial forces to viscous forces. The Reynold’s Number is also used to classify laminar and turbulent flow values. When working with pipes that have different
References: H408 Friction Fluid Apparatus User Guide. TecQuipment LTD 2008.