19.5.1. Major and Minor Losses in Pipes

Now let us go to the minor losses in the pipe systems. As I told it when you have the pipes, it can have a regions you have a smaller pipe to bigger pipe or bigger pipe to the smaller pipe. When you have a these conditions that means the flow is coming it here and going out, the smaller diameters and the larger diameter. If you have these conditions, what we do it that when you compute the energy losses, for this total regions, we compute the analysis this.

In pipe systems, when fluid flows from a larger to a smaller diameter or vice versa, energy losses can occur. These losses are influenced by various factors, including the pipe's geometry and flow characteristics. Energy losses are calculated across these transitions to assess the efficiency of the fluid movement.

Think of a water slide in a water park. If the slide is wide at the beginning and then narrows down, the water rushes faster through the narrow part. However, if the transition is abrupt, some energy is lost due to turbulence and friction, just like in fluid dynamics.

So we can quantify it or you conduct the experiments. It is very easy to conduct the experiment of different pipe diameters, different configurations you can compute it. You just measure the pressure at these two points and you know the velocities like the manometers you can put it then you can measure the pressure difference and you can easily quantify that how much of K value from experimentally.

In terms of fluid mechanics, there are two main types of losses: major losses, which are primarily due to friction in the pipes, and minor losses, which are due to fittings, bends, valves, and other disturbances in the flow. Conducting experiments with different pipe setups allows us to measure these losses accurately, particularly by measuring pressure differences at set points using manometers.

Imagine a garden hose with a nozzle at the end. When you cover half of the nozzle’s opening with your finger, you create a restriction that increases pressure in the hose but also leads to a loss of flow speed. Here, the friction from the hose and the restriction at the nozzle represent major and minor losses, respectively.

Now let us look it how would it happens it. That again I am considering virtual fluid balls okay. If I consider the virtual fluid balls, the balls which is going very close to the wall, which will go straight and inject here as a tangential and go like this, okay. What will happen to this? Here also we have the particular liquid, but that liquid will have a vortex formation. They will start rotating it, start rotating it. So immediately your flow will pass this, these regions will have a vortex formations.

When fluid flows close to the pipe wall, it can create vortex formations due to changes in flow direction or velocity. These vortices contribute to energy losses because they disrupt the smooth flow of the fluid, which can lead to increased turbulence and friction.

Consider stirring a cup of coffee. As you stir, the coffee develops whirlpools. These disturbances create a chaotic flow, analogous to how vortices in fluid systems create additional friction and energy loss, making it harder for the fluid to flow smoothly.

Now if you look it that the because of this mixing layers, because of the vortex formations, and the presence of the vortex formations you can feel it if you are engineers just touch these pipes, you can see this heat is generating it. You can see the temperature difference. So that means, indirectly it indicates for us there is a vortex formations are happening it.

Bends in piping systems can cause additional energy losses due to the creation of vortices. These vortices result in turbulence, which not only hinders flow but can also generate heat due to friction. Understanding these phenomena helps engineers design more efficient piping systems by minimizing sharp turns.

Think of driving a car around a sharp curve. As you turn, you feel the forces pushing you outside the turn. Similarly, in pipes, bends can push the fluid in unwanted directions, creating vortices that cause energy loss and potentially even overheating in the system.

But interestingly let us go for that is two systems okay, which I intentionally putting to you that just look at these figures. One is expansions another is contractions. The flow is comes from this side and goes like this side. In this case also flow goes like this. Now if you look at the steamlines, which is just closer to the wall, in this case, it happens like this.

When fluid flows through sections of varying diameter—either contracting (narrowing) or expanding (widening)—energy losses differ. Contracting flows tend to create more significant vortex formations, leading to higher energy losses compared to expanding flows, where these formations are minimized.

Consider a funnel. When pouring water into a narrow neck (contraction), water tends to splash and create turbulence. However, as the funnel opens up, the water flows smoothly out, demonstrating how expansions can help reduce turbulence and energy loss.

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