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To: theodore bobich who wrote (2212)	2/23/1998 7:27:00 PM
From: shashyazhi	Read Replies (3) \| Respond to of 6464

The pulse charging technology will definitely work on larger engines. While I was studying the math and physics of pulsejets a few years ago, I applied them to a large device called a ground level flare. We were using this flare to burn off excess methane gas at a sewage treatment plant. The local property owners were complaining about the subsonic vibrations created when the flare would start to pulse at its resonant frequency. It would shake the glass in their windows. The engineers were finishing up their analysis when I told them that I had calculated the resonant frequency of the pulsing at about 8 pulses per second, just about a perfect frequency to annoy the neighbors. It shakes the ground, but cannot be heard. The chief engineer told me that it actually pulsed at 4 cycles per second. He said, "We sure could have used you when we designed this thing." I had also calculated the amplitude of the pulse, based on the mass of air being passed through the system on each cycle. One of the most bizarre contentions about the flare was that it would eventually cause an earthquake as it continued to shake the ground! No way. The amplitude of the pulse was about 1000 pounds repeated 4 times per second. To understand how the pulse charge technology works, the simplest model I can think of is a single cylinder engine. Imagine the intake system as a flask or container of constant volume, resonating at a certain frequency. Imagine the exhaust system as a similar flask, again resonating at a certain frequency. Pulses of air are moving back and forth in the intake flask, and pulses of exhaust gasses are moving back and forth in the exhaust flask. Imagine a third flask, which is the cylinder. It is continually varying in volume. The task of the engineer designing a pulse charge engine is to coordinate the pulses in these three vessels so that a pulse in the intake system reaches the open intake valve during the overlap period when both valves are open. If another pulse can reach the cylinder AFTER the exhaust valve has closed, it will have a supercharging effect! And the motions of the piston must be taken into account as well. At at certain point in the power stroke of an engine, the piston is travelling so fast that it gains little by holding the exhaust valve closed. Therefore, the exhaust valve must be rapidly opened, to put the inertia of the expanding gasses to work. This is the initiation of the exhaust side pulse. The exhaust pulse will rebound from the end of the exhaust pipe back to the exhaust valve just before it closes. In carbureted engines, this pulse will drive unburned mixture back into the cylinder. In direct-injected engines, the fuel will not be injected until both valves are closed. The intake side pulse is achieved by rapidly closing the intake valve, sending a pulse back to the entrance of the intake tract. Analysis of pulse charging is easiest with a single cylinder engine or in those engines which have one carburetor and one exhaust pipe for each cylinder. Engines which have intake and exhaust manifolds will have more complex pulsing modes. However, this type of engine will have a flatter torque curve, while the former type will have more peak horsepower. Also, the amplitude of the pulse will depend on whether the engineer chooses to use the natural frequency of the intake or exhaust system, or if he intends to use the first harmonic. A pulse charging system using the natural frequency of the vessels might have very long intake and exhaust tract lengths and be difficult to fit into an existing engine compartment.