Andrew (Gabriel) Livshits
Recently, scientists and energy working hard to process optimization problems most cost-effective options for energy
Development of rotational or spin, detonation engine (Rotating Detonation Engine, RDE), by the Scientific Research Laboratory (NRL), U.S. Navy. According to preliminary calculations, laboratory, RDE will be ten percent stronger and 25 percent more economical than currently used conventional gas turbine engines. True, the general principle of the power plants will remain the same - the flow of gases from the burnt fuel will continue to rotate the blades of the gas turbine.
According to the NRL, even in the distant future, when all the ships of the U.S. Navy will be driven by electricity, power generation will still provide gas turbines, can be structurally altered slightly. Currently, the U.S. Navy uses a gas turbine engine 430 to 129 ships. Each year, they consume fuel at two billion dollars. In the future, conventional internal combustion engines on the ships will be replaced with RDE, that is, it is about modernization. Nevertheless, the principle of prospective power plants and modern engines are quite different.
Today, internal combustion engines operate on the Brayton cycle. Simplifying its essence lies in the sequential mixing of fuel and oxidant, compressing the mixture, its arson and burning with subsequent expansion of heated products of combustion. Such an extension, is just used to perform mechanical work (movement, rotation of the turbine, the pistons), gives a constant pressure. Combustion front in the fuel mixture moves at subsonic speed, a process called deflagration.
Newer engines scientists intend to use detonation explosive burning fuel mixture at which the reaction is distributed through the material at a supersonic speed. The phenomenon of detonation is not fully studied yet, but it is known that in this matter by burning propagating shock wave, followed by a chemical reaction in the fuel mixture with the release of a large amount of heat. When a shock wave passes through a substance is heated and can detonate.
In the RDE will be used achievements obtained during a pulse detonation engine (Pulse Detonation Engine, PDE). It works by that is injected into the combustion chamber pre-compressed fuel-air mixture, it is burning, and the mixture detonates. In the nozzle, combustion products expand that and perform mechanical work. Then the whole cycle repeats. Lack of PDE is the relatively small magnitude of pulsations (repetition of cycles).
Furthermore, the design of these engines with increasing frequency ripple becomes more difficult. In particular, it is necessary to synchronize the valves responsible for the injection of the fuel mixture, by the detonation cycle. Pulse detonation engine itself is extremely noisy, consume a lot of fuel, and for it to work requires constant supply of fuel dosage and initiation of each cycle of the detonation. Simply put: the combustion chamber got fuel, it was set on fire, it will detonate, and then repeated.
The principle of rotating detonation engine is somewhat different from PDE. It realized the possibility of constant undamped detonation fuel mixture in the combustion chamber of the ring. The first time such a phenomenon called spin, or rotate, detonation, in 1956 described the Soviet scholar Bogdan Wojciechowski. The very phenomenon was discovered in 1926 in the UK - it was noted that in some systems instead of the expected plane detonation wave emerges a bright "head", the rotating spiral.
Thanks photographic own invention Voitsekhovsky managed to photograph the front of a shock wave moving in the fuel mixture in the combustion chamber of the ring. In contrast to the plane detonation in spin detonation occurs only transverse shock wave followed by a layer of unreacted heated gas, and then the chemical reaction zone. Such a wave "runs around" annular combustor. Marlene Topchiyan, Professor, Institute of Hydrodynamics Lavrentiev, which has long worked Wojciechowski, described the camera as the "flattened donut."
To obtain a rotating detonation in an annular combustion chamber radially fed fuel mix (with fuel and oxidizer can come apart and their mixing and compression provides a detonation wave). In an interview with "Science in Siberia" Topchiyan told that as long as the detonation wave "runs around" an annular combustion chamber, the fuel mixture for it to refresh - "each time before the wave is a fresh mixture." Manner and ensured steady detonation.
In contrast to the Brayton cycle, in which the pressure in the system after the combustion of fuel remains constant, the detonation of the chemical combustion of the mixture in the combustion chamber pressure is not much time to change, but then increases abruptly at times and may exceed one hundred atmospheres. What's interesting, to rotary detonation engines are fully applicable technology engines Brayton cycle. In particular, the use of RDE compressor increases the efficiency and capacity of the system as a whole.
Detonation engine, by the way, has already been used. In particular, one embodiment of such a power plant - a pulsing jet engine - used in the German cruise missiles "V-1" at the end of World War II. It was simple to manufacture, is unpretentious, but is not very reliable for more serious problems.
In 2008, the first flight of an experimental aircraft made Rutang Long-EZ with pulsed detonation engine. The engine worked for ten seconds, the plane was flying at an altitude of 30 meters. PDE on the experimental aircraft had four tubes in which the cycles of detonation occurred with a frequency of 80 hertz. The power plant was able to develop a thrust of 890 Newtons. For comparison, each engine of the MiG-29 develops a thrust of 81.4 kN.
Engines of the future
Experimental model RDE, created Research Laboratory U.S. Navy, is an annular conical combustion chamber with a diameter of the injection of the fuel mixture is 140 millimeters, and from the nozzle - 160 millimeters. The distance between the walls of the combustion chamber is ten millimeters in length "tube" 177 millimeters.
The fuel is a stoichiometric mixture of hydrogen and air (oxidant contained in it only as much as is necessary for complete combustion of the fuel). The fuel mixture is fed into the combustion chamber at a pressure of ten atmospheres, and the mixture itself has previously heated to 27.9 degrees Celsius. A mixture of hydrogen and fuel is the most convenient for the study of spin detonation, however, according to the NRL, in advanced engines can use regular fuel in a mixture with air.
Preliminary tests of the RDE, created NRL, demonstrated the efficiency of the detonation of one cycle at 30 percent (efficiency Brayton cycle was taken as zero percent). When you add in the compressor efficiency Brayton cycle can be increased, and this usually works for systems based on the cycle of detonation. RDE abrasion resistance compared to PDE above, because they detonation wave "go" along the walls of the combustion chamber and the shock effect on them is significantly lower.
According to the NRL, the process of combustion of the fuel mixture in the RDE is heterogeneous, and it contains the field of deflagration, but their share in the overall process of combustion is only 14 percent. Optimization of engine design and selection of the ring diameter of the combustion chamber and the gaps between the walls can reduce this figure. The advantages of long-term motor NRL carries substantial fuel savings (to initiate a new cycle of the detonation of the combustible mixture requires less).
Expanding in the nozzle of the combustion products can later thanks to Coanda effect, collect with a cone in a single gas jet and direct it into the turbine. Flowing from the nozzle gases will rotate it, part of the turbine can be used for the movement of the ships, and some - to generate the energy required to ship systems and equipment.
Own spin detonation engines can be built at all without any moving parts, which simplifies the design and reduces the final cost of the power plant as a whole. However, before you talk seriously about the prospects of series production of rotary engines, scientists have to solve several problems, the most difficult of which is the selection of heat-resistant and durable materials.
In RDE detonation stability can be maintained until the end of the fuel and heating the structure to disintegration. The latter can also be used technology successfully used to cool the turbine blades, for example, in air-breathing engines. Over time, the new engines will be installed not only on the ships, but the promising aircraft. Thus, the backup can be restored to life project Blackswift - machine capable of speeds up to Mach number of six (about seven thousand kilometers).
Currently RDE considered the most promising type of internal combustion engines. Their development, in particular, has been the University of Texas at Arlington. It creates the power plant is called "continuous detonation engine" (Continuous Detonation Engine, CDE). Scientists from the university also are experimenting with different diameters and annular combustors with different fuel mixtures, which contain hydrogen and oxygen or air in different proportions.
Meanwhile, in 2007, it was invented a device that pretty much solves the problem of the combustion chamber, operating in a stable mode pulsed detonation
Development of a series of preliminary patent applications, the following invention was acquiring for Ukraine and Eastern European countries of great importance in view of the fact that the explored in Ukraine shale gas can, when used effectively to radically change the situation with the energy independence of these countries from unfavorable in all respects supply of natural gas from Russia
United States Patent Application 20110126462
Kind Code A1
Livshits; David; et al. June 2, 2011
Device for Producing a Gaseous Fuel Composite and System of Production Thereof
The invention relates to a gaseous fuel composite, a device for producing the gaseous fuel composite, and subcomponents used as part of the device for producing the gaseous fuel composite, and more specifically, to a gaseous composite made of a gas fuel such as natural gas and its oxidant such as air for burning as part of different systems such as fuel burners, combustion chambers, and the like. The device includes several vortex generators each with a curved aerodynamic channel amplifier to create a stream of air to aerate the gas as successive stages using both upward and rotational kinetic energy. Further, a vortex generator may have an axial channel with a conical shape or use different curved channel amplifiers to further create the gaseous fuel composite.
Now, for more on this group of preliminary and provisional inventions
In the combustion of gaseous fuel composite, which is introduced into the flame zone of the formation in the form of a homogeneously mixed vortex tube, the torch has the most compact form - a sphere in which the fuel continues vortex rotation, uniformly mixed with air
Combustion occurs uniformly over the entire volume of the sphere and the relationship between the three-dimensional model of the spatial arrangement of the molecules of gas molecules of air during the combustion cycle does not change
Rotation with a high linear velocity multiple streams in a minimum volume creates harmonious pulsating phenomena whose frequency is so high that the intervals between pulses are negligible
These phenomena are the combustion of gaseous fuel composite in a constant volume at a constant speed of fuel surrounded by an oxidizing agent in a minimum volume of the flame, with a high pulse rate when the flow direction of the composite in a burning flame structure
A ll it causes fever in the volume of the flame and creates the conditions for Constant volume combustion or HUMPFREY CYCLE
NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE is BURNER, which has all the features characteristic of a typical device for efficient combustion of natural gas
Fuel mixture is fed into the flame zone of formation of gaseous fuel in the form of composite
Flow of gaseous fuel is an integrated composite vortex tube, which consists of at least 60 local vortex tubes, with equal geometric and aerodynamic characteristics
Starting from the basic performance of the device name can be represented as follows: VORTEX TURBO BURNER
The device can be adapted to the VORTEX ATOMIZER
To VORTEX ATOMIZER can be served extra airflow, if the eddy generators served less than 100% of% STOICHIOMETRIC AIR
The device can operate on various combinations of the proportions of natural gas and air, including 100% STOICHIOMETRIC AIR
The product gas mixed with air forming gaseous fuel dynamic composite combined stream which has the shape of the vortex tube
Despite the difference in the proportion of air and natural gas, in a vortex tube homogeneity of the mixture is maintained by the dynamic qualities and aerodynamic flow composite
NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE
The device consists of several concentric vortex generators, each of which has 15 tangential channels forming the local coaxial vortex tubes of a homogeneous mixture of natural gas and air
The device consists of only 4 original details - the vortex generator casing, tubing and pipes input output
The simplicity of design determines the reliability and low cost of manufacturing, ease of integration into the boiler or other object thermodynamic
EVALUATION OF NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE LIKE NEW PRODUCT
The device is a new type BURNER, which implement more effective when working HUMPFREY CYCLE
The device produces a homogeneous gaseous fuel composite that is served and consumed in a vortex tube
The device works effectively without air
The device is stable, repeatable main operating parameters and performance while reducing or increasing the flow of natural gas, more than 90%
All this allows the unit to qualify as a new product, - VORTEX TURBO BURNER
EVALUATION OF THERMODYNAMIC WORKING CYCLE OF NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE
The device has at all stages of functional cycle constant volume and constant relationship between the amount of process components
By volume, flow rate, pressure, linear velocity, temperature, and changes in the components of the composite produced gaseous fuel
By volume, flow rate, pressure, linear velocity, temperature, and changes in the gaseous fuel in the local composite vortex tubes and vortex tube integrated until the ignition
By volume, geometry, linear velocity of flow, pressure, uniformity, temperature flame from ignition to complete the combustion process
For uniformity, the amplitude and frequency distribution of harmonic pulsations in the amount of the flame
All these factors determine the state of the combustion process in the device as a CONSTANT VOLUMETRIC COMBUSTION
EVALUATION OF COST FACTOR OF NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE
Manufacturing cost VORTEX TURBO BURNER is about 10 times smaller than any known device of this class
This, combined with the rest of the workers and the functional advantages, allows cost effective use of VORTEX TURBO BURNER the modification of the existing fleet of boilers and other thermodynamic devices
GENERAL ADVANTAGES OF VORTEX TURBO BURNER WITH VORTEX ATOMIZER THAT BASED ON NATURAL GAS WITH AIR VORTEX MIXING AND ACTIVATION DEVICE
The device has no moving parts
The device has a compact dimension features
The device can be adapted to any constructive and technological conditions of equipment, which is subject to modernization
The device can work efficiently without additional air
When working without air, the unit can save up to 17% of natural gas
The device provides more than the existing flame temperature with an equal volume of the flame
The device works with the workers and functional characteristics equivalent HUMPFREY CYCLE, which is on the thermodynamic characteristics of at least 10% more efficient than BRAYTON CYCLE - on which work all known devices
Flame produced by the device has a spherical shape, which at higher temperatures, provide CONSTANT VOLUMETRIC COMBUSTION, the concentration of heat energy in a minimum volume and lower energy losses
Since the device has a constant scale factor, it is equally effective for all costs of natural gas
This allows us to replace the modernization of a very complex and expensive devices (such as the company's devices CLEAVER BROOKS) at a simple, reliable and low-cost and more efficient VORTEX TURBO BURNER