Why is the loss more in a sudden expansion than sudden contraction?
The flow pattern after the vena contracta is similar to that after an abrupt enlargement, and the loss of head is thus confined between Sec. c-c to Sec. 2-2. Therefore, we can say that the losses due to contraction is not for the contraction itself, but due to the expansion followed by the contraction.
How can head loss due to sudden change in cross section be minimized?
These losses can be reduced by installing nozzles or diffusers between the different cross sections. It makes the transition more gradual. The head loss in a bent pipe is more than a straight pipe of the same length.
What is a sudden expansion?
Description. The Sudden Area Change (TL) block models the minor pressure losses due to a sudden change in flow cross-sectional area. The area change is a contraction from port A to port B and an expansion from port B to port A. This component is adiabatic. It does not exchange heat with its surroundings.
What is meant by Bernoulli’s Theorem?
Bernoulli’s theorem is the principle of energy conservation for ideal fluids in steady, or streamline, flow and is the basis for many engineering applications. …
Why does head loss increase with flow rate?
A rule of thumb for pipeline head loss is doubling the flow rate increases the head loss by a factor of four. This is because the flow rate is raised to the second power. As Table 1 shows, doubling the flow rate doubles the fluid velocity and Reynolds number.
What is the formula for head loss?
Head-loss form Δh = The head loss due to pipe friction over the given length of pipe (SI units: m); g = The local acceleration due to gravity (m/s2).
What happens to the head loss when the flow rate is doubled?
What happens to the head loss when the flow rate is doubled? Explanation: If the flow rate is doubled, the head loss increases by a factor of four. Since, the head loss is directly proportional to the square of the flow rate.
Why is head loss important?
The head loss also represents the energy used in overcoming friction caused by the walls of the pipe and other technological equipments. The head loss is unavoidable in real moving fluids.
What is the significance of changes in temperature to the head loss?
Both density and viscosity decrease with an increase in temperature, which means they have competing influences on the head loss. To determine which has the dominant influence, the head loss must be calculated for a given change in temperature (and corresponding changes in density and viscosity).
What is the head loss in pipe flow?
The pipe head loss is the frictional loss in the hydro pipeline, expressed as a fraction of the available head. Water (like any viscous fluid) flowing through a pipe experiences a loss in pressure due to friction.
What affects head loss?
Overall head loss in a pipe is affected by a number of factors which include the viscosity of the fluid, the size of the internal pipe diameter, the internal roughness of the inner surface of the pipe, the change in elevation between the ends of the pipe, bends, kinks, and other sharp turns in hose or piping and the …
Which are the major losses?
The friction loss in uniform, straight sections of pipe, known as “major loss”, is caused by the effects of viscosity, the movement of fluid molecules against each other or against the (possibly rough) wall of the pipe. Here, it is greatly affected by whether the flow is laminar (Re < 2000) or turbulent (Re > 4000):
Why a minor loss occurs?
Minor losses are local energy losses caused by the disruption of the flow due to the installation of appurtenances, such as valves, bends, and other fittings [5]. There are two methods used to calculate the minor losses, the equivalent length method and the resistance coefficient “K” method.
What are the types of minor losses?
There are three types of forces that contribute to the total head in a pipe, which are elevation head, pressure head, and velocity head. Minor losses are directly related to the velocity head of a pipe, meaning that the higher the velocity head there is, the greater the losses will be.
What do minor losses apply to?
Minor losses in pipe flow are a major part in calculating the flow, pressure, or energy reduction in piping systems. Liquid moving through pipes carries momentum and energy due to the forces acting upon it such as pressure and gravity.