1) Before actually attempting to understand how the Rotary Pulse Jet Engine or the Concept IC engine or any of the other engines featured at this site work , it is necessary to understand the Golden rule of physics , which put simply is "nothing for nothing is the rule in physics" . i.e you don't put anything in you can't get anything out , this applies to energy and power and everything else.
2) The Rotary Pulse Jet Engine has an efficiency of 65% or greater as compared to the 22% or so of the conventional reciprocating internal combustion engine. This means that it develops about 250 hp at 2400 rpm , as compared to the 17.5 hp- 25 hp horsepower of an ordinary 4 x 4 , 4 cylinder IC engine. The Rotary Pulse Jet engine not only develops this much power ( see equations given later on this page ) but does it in a much shorter time. Therefore it is possible to feed this extra energy to a fly-wheel , and then switch the engine off and allow the fly-wheel to run the engine for the greater part of the time , because of its design , the RPJ can also renew the momentum of the fly-wheel from time to time in bursts lasting a few seconnds or even fractions of a second to keep the momentum fo the fly-wheel going at a steady rate.
3)The De Laval Nozzle :- The use of a nozzle to accelerate the gases of combustion is an important aspect of the engine design , for instance when Robert Goddard was first experimenting with his rocket engine , he found that without a nozzle only about 2% of the energy contained in the fuel was being used to generate thrust , once he started to use the De Laval nozzle the energy used to develop thrust went up to 61% making it the most efficient engine of all the engine designs which had so far been developed including the IC engine 20% and the Diesel 40% under ideal conditions. Robert Goddard experimenting with the relatively crude equipment available in the twenties managed to get exhaust velocities of 8000 ft/sec . (which is why I have used this figure).
4) Equations showing the power developed by the RPJ The RPJ is an impulse engine . Examples of impulse motivated machines are pelton wheels , De Laval turbines and so on. The equation for impulse is given by :-
I = mv - mu ,
where I = Impulse , mv equals final velocity and mu equals original velocity.
The momentum mv of the RPJ is calculated by m x v ,
where m stands for the mass of the gases being combusted
and v stands for their final velocity.
Mass = 0.0176 lbs
Velocity = 8250 ft/sec
Revoultions per sec = 40. (i.e 2400/60 rpm)
Momentum = 8250 x 0.0176 = 145.2 lbs ft(torque)= 14.52 ft lbs (absolute )
In one revolution 4 x 14.52 = 58.08 ft lbs.(absolute units)
In one sec the engine develops 58.08 x 40 = 2323.2 ft lbs.
In horse power this works out to 2323.2 / 550 = 4.224 hp.
In one minute (i.e hp per rpm ) = 4.224 x 60 = 253 . 44 hp.
Note by increasing the size of the cylinder it will be possible to get more power.Alternatively an air-compressor and tank maybe used with exactly the same result. Another option is a turbo-charger or a super charger.
5) By now it should be clear that in the rpj excess energy is fed into the fly-wheel which later delivers this stored energy until frictional losses dissipate it. The question that every one wants to know the answer to is how long the fly-wheel can sustain the energy out-put level needed to run a car . The answer is on a level road going at about 40 km/h in a car weighing about 2500 lbs , running at 2400 rpm , a fly-wheel can sustain the load for about 30 seconds at a time. This translates into what could represent a terrific saving in fuel . If there is any doubt about this at all , there are numerous companies offering fly-wheel powered UPS systems that can sustain a power of 1 KW (1.88hp)for 10 - 15 seconds , the fly-wheels in question are generally 2 ft in diameter and are spinning at about 3600 rpm , just get in touch with one of these companies and ask about the load bearing capacity of their fly-wheel UPS systems. Now the point here is that a car moving on a level road at uniform velocity , needs only enough power to overcome frictional forces to maintain its speed , since at these low speeds air - resistance is negligible . Typical figures for a car moving at 40km/hr and weighing about 2500 - 3000 lbs would be about 128 ft lbs of energy , which is about ¼ hp . Now suppose the fly-wheel has an energy of 8 hp it means that it can sustain a load of 1/4hp (i.e (550 x 8 = 4400) / 128 = 34 secs approx. Note that while slowing down or stopping the momentum of the fly-wheel is used regeneratively to generate electricity which is fed to the battery.
Pros And cons of the Rotary Pulse Jet Engine:-The main disadvantage of the Rotary Pulse Jet Engine is the very high speed of the rotor , which at 2400 rpm is equal to about 250 ft/sec , thus each complete rotation of the rotor takes place in approx . 0.025 secs , since there are four combustions per rotation this means each combustion has to take place in 0.006 secs , about 1/150 of a second . However , having said this , I have to admit that this might be overstating the case , for instance Wankel engines , with rotor dimensions of 7" radius regularly run at 10,000 rpm ! Which means that the rotor tip speed achieves 523 ft/sec. Since the Wankel engine has been in production in some form or the other for the past 50 years or so. I would have to go with this figure , which means that the Rotary Pulse Jet is very much a practical possibility.The very high rotor speed means that the valve can be designed to catch as much air and fuel as possible in the given time in the manner of a ram jet because it is moving at such a high speed that air/fuel will be forced into the cylinder by the speed of the rotor . The high rim speed can also be considered to be an advantage because it means that the engine can store a lot of its energy in a fly-wheel and draw this energy of as needed.
Here is an excerpt from Canadian Driver about high rpm engines:-
October 2, 2002
The science of high-revving engines
BMW has broken a barrier. Their Formula One engine has passed a 19,000 revolutions per minute threshold for the first time. For an automotive engine, that is astounding. Think of it this way. 19,000 rpm's means 9500 ignitions a minute in each of the ten cylinders. That's 158 per second, or one ignition every 6 thousandths of a second. Blink and each engine cylinder has fired a dozen times!
An even more impressive way of looking at it is that every 6 thousandths of a second, air and fuel are drawn into the cylinder, compressed, ignited, had the flame front cross the cylinder, had the combustion gases expand, and exhausted the waste gases.
6) The Concept IC Engine :-works on exactly similar principles , although in this instance the high velocity exhaust gases ,when vented through a De laval nozzle are used to drive a turbine , as they were originally designed to do , which in turn would supply the electrical power to drive the car. The IC unit wopuld therefore function as the burner unit of the the turbine. The turbine part of the engine which would provide the electricity to motivate the car would be in the form of turbo-generator which would provide about 80 KWs of electricty which is more than sufficient to power a car. Turbo-generators are getting smaller and smaller in size making the whole design possible. For instancce a conventional generator providing about 50KW would normally weigh 2 tons and occupy the space taken by a small car. A turbo-generator would weigh only about 100 – 150 lbs and would be about the size of a normal car alternator.Click for more information(Select core technology )
The Concept IC Engine , which is in effect a very efficient hybrid engine , should be less of a problem to implement than the Rotary Pulse Jet Engine , since it would work within the same parameters as a normal IC engine , with the difference that it would operate at an optimal speed , the car would even make it possible to take it home park it in the garage and run the whole electrical system needed to run a home off it. The advantages of the Concept IC Engine are that it would be pollution free and far more efficient than an IC engine , it would be noisless and without vibration and would have an excess of electrical power on board the only draw-back being that its fuel efficiency would be only slightly greater than that of a conventional IC engine.