How Tomorrow’s Engine Works
Tomorrow’s Engine, as described in this article, has many unique features. It is a constant RPM engine. Top speed of parts in the engine is supersonic and independent of size, making small engines rotate with very high RPM. It is capable of high efficiencies (possibly up to 90% with existing materials and manufacturing techniques). Gas temperatures in contact with moving parts of the engine are up to 500K below gas temperatures in contact with moving parts in other engines. This is possible because more than half the energy added to the gas and removed from the gas by moving parts is kinetic energy from supersonic gas. It has few parts and is thus lightweight, delivering more power than other engines (even turbines) of comparable weight. The hottest parts of the engine do not require cooling.
The Fundamental Difference Between a Turbine and Tomorrow’s Engine
Both a turbine and Tomorrow’s Engine impart energy to gas through rotation. A gas turbine drives air axially, and is driven by axially moving combustion products. In a jet engine air enters and leaves on roughly the same axis. Tomorrow’s Engine incorporates two roughly pyramidal rotors and the hollow shaft inside those rotors into components we refer to as “spinners” which contain the circulating gas flow and force it to match their rotational speed. One is the compressing spinner which contains the gas flow as the gas travels away from the axis, accelerating it circumferentially to add energy. The other is the power output spinner which contains the gas flow as the gas moves toward the axis, decelerating it circumferentially to take off energy. Each spinner is a rotating container with separated roughly radial pathways for the gas to travel through radially, which will be accomplished by radial holes through shaft walls or passages defined by radially oriented blades and walls.
What Tomorrow’s Engine Looks Like & How It Works
The engine consists of a long shaft on which are found the roughly pyramidal compression spinner and power spinner. While the compression spinner does all the work needed for compression, producing supersonic rotational speed , most of the compression takes place outside the compression spinner as the supersonic gas slows down, first to subsonic speed in a surrounding ring called the compression annulus, and finally to least speed in the heating chamber. The compression spinner and annulus are smaller than the power spinner and annulus. After the compression spinner adds energy by circumferentially speeding up the moving gas, additional heat energy is then added at constant pressure burning fuel. This energy is converted into rotational power in the power spinner by the moving gas in a time reversal of the compressing spinner in larger parts at higher speeds.
The supersonic gas, slowed down by the power spinner, drives the rotary motion of the shaft. The rotary motion of the shaft both drives the compression side of the engine, and does work outside the engine itself because the shaft is connected to outside equipment, usually an electric generator which also acts as the starter motor.
Figure 1 shows the shaft with the spinner blades attached. The thinner section of the shaft is for the compression spinner, and the thicker section of the shaft is for the power spinner. Radial holes in the shaft (not shown) are part of the spinners. The shaft is solid between the spinners.
A key feature of the engine is the temperatures the moving parts experience, which are considerably lower than corresponding temperatures in piston engines. The parameters used are the following.
T0 = atmospheric temperature in degrees K
R1 = radius of compression spinner
R2 = radius of power spinner
γ = polytropic constant
SoS = speed of sound
ω = angular velocity of shaft
R = radial distance from shaft
The temperature inside the compression spinner at radial distance R is given by
The temperature inside the power spinner at radial distance R is given by
Figure 2 shows the shaft and the spinners (blades are inside the spinners), and the basic flow of the gas through the engine is indicated by arrows. Red arrows indicate that the gas is heating, blue arrows indicate that it is cooling.
The Compression Side of the Engine
The gas enters the compression spinner and travels outward while rotary motion speeds it up. The shaft turns very quickly, so that before the gas reaches the rim of the compression spinner, it is rotating at supersonic speed, which also heats the gas. The gas then emerges from the spinner into the compression annulus, designed to slow the gas down to subsonic circular speed and convert its energy of motion into heat. The gas spirals outward a few times around the annulus before entering an exit vent and reaching final compression in a heating chamber.
The Heating Chamber
The heating chamber is sized to make the subsonic flow from the annulus slow to far below the speed of sound in the hot gas, converting almost all the kinetic energy of the gas into temperature energy. The gas slows in the heating chamber and reaches its maximum compression temperature.
Figure 3 shows the stationary annuli surrounding the rotating spinners. These are open rings that high speed gas spirals through, outward in the compression annulus and inward in the power annulus. The gas is supersonic next to the rotor and subsonic at the outer rim where vents collect the flow into subsonic tube flow through connecting tubes. Flow is reversed on the power side.
Figure 4 shows a cross-section of the engine showing shaft, rotors, and annuli. After reaching maximum compression temperature, additional heat is supplied by burning fuel. This gives the gas the extra energy with which to do work outside the engine.
Figure 5 shows the configuration of the entire engine, with the heating chamber located in the center, connected by tubes to each of the annuli. The shaft and the spinners turn, but the annuli, heating chamber, and connecting flow tubes are stationary.
Using the previously-defined parameters, the temperature in the compression annulus at radial distance R is given by
The temperature in the power annulus at radial distance R is given by
The input stagnation temperature Ts1 in the heating tube is given by
And the heated stagnation temperature Ts2 in the power annulus is given by
Beyond the Heating Chamber
The gas now goes through a process in the power section of the engine which mirrors in reverse what happens in the compression section, with larger parts at higher speed. After the gas has been completely heated, it goes through a speed-controlling vent at subsonic speed into the power annulus, larger than the compression annulus, which surrounds the larger power spinner, where the gas spirals inward. The gas speeds up in the annulus to supersonic, like air speeding up going into the bottom of a tornado, and matches the speed of the power spinner as the gas enters it. The gas is slowed to the rotational speed of the spinner which turns the shaft, and then emerges as exhaust from the right side of the shaft in Figure 4.
Although the current version of the engine is an internal combustion engine, the design can be used to create a high-efficiency engine powered by solar heating. In order to achieve efficiencies of 80% or higher, the engine will be constructed of ceramics rather than metal, and will be powered through external heating of argon to reduce pressures and stresses. The entire engine will be self-contained to enable the argon gas to be recirculated from the exhaust to the intake, where it will be used again. In a solar version of the engine, the heating chamber is the heat collector inside a box receiving the collected sunlight. Ordinary atmospheric cooling in shaded pipes, water cooling, or a heat exchanger may be used to cool argon exhaust back to atmospheric temperature before it is returned to the engine.