Measuring and testing – Internal combustion engine or related engine system or... – Compression
Reexamination Certificate
2000-01-21
2003-01-21
Raevis, Robert (Department: 2856)
Measuring and testing
Internal combustion engine or related engine system or...
Compression
Reexamination Certificate
active
06508112
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a measurement system and method for probing dense, high pressure sprays and, more particularly, to a tomographic spray momentum mapping system, which utilizes a mechanical wire probe to obtain spray momentum measurements throughout the spray and a computed topography software program for processing and integrating these measurements for mapping the spray momentum distribution.
BACKGROUND OF THE INVENTION
A compression-ignition (“CI”)engine, first developed for diesel fuel, is an engine that does not use a spark to ignite fuel. When air is compressed and fuel is injected into a CI engine, the fuel ignites. A direct-injection (“DI”)engine is an engine in which the fuel is injected by mechanical action into the combustion chamber. Compression-ignition, direct-injection (“CIDI”)engines are used predominantly in the trucking, rail and shipping industries.
The recent development of high-pressure, electronically-controlled injection systems has made it possible to improve CIDI engines to the point where they are suitable for use in passenger vehicles as well. The outstanding benefit of this type of engine is its very good fuel economy, which has the potential to significantly reduce the nation's fuel use, as well as reducing the production of carbon dioxide by passenger vehicles. The drawbacks of CIDI engines are its high emissions, primarily nitrous oxides and particulates, for which satisfactory exhaust after-treatment does not yet exist.
In order to further improve the efficiency and to reduce emissions in CIDI engines, it is necessary to understand the fundamental physical processes that take place in the engine's combustion chambers. Formation and destruction of pollutants are controlled to a great extent by the mixing process. In turn the efficiency of in-cylinder mixing is dependent upon the fuel spray created by the fuel injector. In order to reduce the amount of pollutants formed by the engine, it is advantageous to study the characteristics of the fuel spray structure. Fuel spray studies provide insight into the spray-gas mixing process and facilitate development and evaluation of new injection hardware and fuel injection strategies. Such analysis can also provide data for the development and improvement of computer models of the spray and its combustion.
Because of the lack of experimental tools suitable for probing dense, high pressure fuel sprays, researchers currently lack information necessary for the improvement of engine performance. Thus, the present tomographic spray momentum mapping system has been developed to provide researchers with a practical tool suitable for probing dense, high pressure fuel sprays.
The ability to measure momentum distributions in sprays will be of even greater importance in the future if new fuels such as dimethyl-ether or “bio-diesel” fuel gain importance. These fuels generally have physical properties such as viscosity and distillation curves significantly different from those of current fuels. These fuels can markedly change the characteristics of fuel spray and have a substantial effect on combustion quality. Further, it may be necessary to modify fuel injection hardware in order to exploit these fuels making accurate analysis of fuel spray characteristics critical to engine and injection system manufacturers.
DESCRIPTION OF RELATED PRIOR ART
Currently, sprays are primarily studied using optical techniques such as direct imaging and laser Doppler velocimetry. Direct imaging techniques provide information on physical characteristics such as spray penetration, spray angle, the initial dispersion angle of the nozzle, initial spray tip speeds, and total momentum measurement. Doppler velocimetry techniques provide information regarding particle velocity, particle size, spray angle variations and spray asymmetry.
However, because of the high density of diesel sprays, the information obtained by optical techniques is necessarily limited to that which may be obtained in the outer envelope of the spray. These techniques do not provide critical information such as velocity, mass, and droplet size distribution within the spray and, more particularly, near the fuel injector nozzle. A further limitation of optical techniques is that only thin sprays can be studied due to the need for optical transparency of the sprays. In contrast the use of the mechanical spray probe of the present system eliminates the need for optical transparency, and even the interior portions of dense fuel sprays may be investigated.
One example of a prior art method of measuring fluid streams is shown in U.S. Pat. No. 3,338,093 to Usry et al. which discloses a device for measuring the momentum and solidity of fluid free streams from injection valves by causing a wire of generally triangular cross-section to transect the stream in such a manner that the stream impinges on the base of the triangle measuring the position of the wire and the force of the fluid impinging on the wire.
Another example of prior art spray analysis is shown in U.S. Pat. No. 2,756,591 to Hagerty et al. which discloses a spray analyzer that has a probe to be positioned in the spray and that provides a permanent record of the spray performance in the form of a chart reading mass distribution or momentum changes along the ordinate and angular displacement around the circle of a round or conical spray along the abscissa of the chart.
Another example of a prior art spray analysis is illustrated in U.S. Pat. No. 3,449,948 to Willowick et al. which discloses a nozzle spray test device for determining spray cone vertex angle of fuel injection nozzles. In this device the injection nozzle to be tested is clamped in the test device and connected to a fuel pressure source, the conical fuel spray issuing from the nozzle being directed into a chamber having aligned detectors or probes which are adjustable radially inwardly or outwardly to be impinged by elements of the conical fuel spray.
Another example of a prior art device for spray analysis is shown in U.S. Pat. No. 5,753,806 to Ryan et al. which discloses an apparatus and method for determining the distribution and flow rate characteristics of an injection nozzle wherein a plurality of piezoelectric sensors are disposed in a spatial array around the ports of an injection nozzle. Separate electrical signals proportional to the instantaneous momentum of fluid discharged from the injection nozzle and impacting on each of the sensors are used to calculate the instantaneous momentum and mass flow rate of fluid impacting each of the sensors.
Another example of prior art spray analysis is disclosed in U.S. Pat. No. 5,686,989 to Hoffinan et al. which shows a transient spray patternator. This device utilizes a honeycomb structure to collect the spray in individual tubes positioned through a given cross-section of the spray permitting measurement of the mass flux distribution, penetration rates, droplet sizing and distribution within either a steady state or transient spray pattern.
Another example of prior art fluid flow analysis is shown in U.S. Pat. No. 5,663,508 to Sparks which discloses a silicon flow sensor wherein the primary sensing component is preferably formed by a single silicon chip on which associated signal conditioning and compensating circuitry can be provided. The flow sensor is intended for purposes such as determining the flow rate of intake air to an automotive engine.
Another example of prior art fluid flow analysis is illustrated in U.S. Pat. No. 5,120,951 to Small which discloses an optoelectronic motion and fluid flow sensor wherein a resilient member is fixedly supported at one end thereof and entrained in the fluid for varying the amount of light incident on the photosensor from the light source as a function of the amount of deflection of the resilient member caused by motion of the fluid in a passageway.
Another example of prior art fluid flow analysis is shown in U.S. Pat. No. 4,920,808 to Sommer which discloses a device and method for measuring the flow velocity of a free flow in t
Raevis Robert
Rey Clifford F.
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