THE UNIFLOW STEAM ENGINE
I suppose that you could say that there are two different methods of using steam to drive an engine, counter flow and uniflow. As the terms would imply, counter flow could mean, in opposite directions and uniflow could mean in one direction. That is exactly what the terminology means.
When an engine is designed for counter flow operation, steam is admitted, alternately, at each end of the cylinder and is allowed to expand down the length of the stroke. When the piston starts it's return trip, to the end where it took the steam, the exhaust valve, at that end, opens to let the, then low pressure, steam out. In other words, counter flow; out at the same end that it came in. Most engines are designed and operate on this concept.
The Uniflow can be operated either counter flow or uniflow, because it has a set of exhaust valves at ends of the cylinders, as well as a, permanently open, exhaust port at the center. When it is being operated Uniflow, it takes steam at the ends of the cylinders and exhausts through the port in the center, flowing only one way. This means that the piston must be, at least, as long as one half of the length of the stroke, less half of the width of the exhaust port, in order to allow the port to be uncovered when the piston reaches the end of it's working stroke.
Mutual Boiler had two of them insured at the Kahns Packing Company in Cincinnati. They sat, side by side, in the Engine Room. Kahns had built a heavy steel structure over the top of them so that when the Ohio River flooded and backed up Mill Creek, they could connect large chain-falls to the generators and lift them out of danger of the rising water.
HOLD ON!!!, I had every intention of giving a great big explanation about the Skinner Uniflow Steam Engine, such as, why and how the cylinder is bored egg shaped, why they exhaust to a condenser if they are operated uniflow, as well as some of the problems with the, long, heavy piston and a lot of other things, both good and bad. But now it dawns on me that, even though I am familiar with all of those things, there are probably no more than six people in the world that cares, one way or the other.
If there should be anyone that is the least bit interested, they could go to their library and find a better explanation than I could give. So, therefore, I will shut this off, right here, and go on to something else. But let the record show that I think that a little, horizontal, Skinner Uniflow Engine direct connected to a generator (perhaps 500 KW) was one of the nicest pieces of equipment that I have ever seen, in operation.
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