CN111648876A - High-low type double vortex chamber double-reducing combustion chamber - Google Patents
High-low type double vortex chamber double-reducing combustion chamber Download PDFInfo
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- CN111648876A CN111648876A CN202010542285.7A CN202010542285A CN111648876A CN 111648876 A CN111648876 A CN 111648876A CN 202010542285 A CN202010542285 A CN 202010542285A CN 111648876 A CN111648876 A CN 111648876A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/26—Pistons having combustion chamber in piston head
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
- F02F3/00—Pistons
- F02F3/24—Pistons having means for guiding gases in cylinders, e.g. for guiding scavenging charge in two-stroke engines
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- Combustion Methods Of Internal-Combustion Engines (AREA)
Abstract
The invention provides a high-low type double vortex chamber and double-throat combustion chamber, wherein vortex chambers are distributed in a high-low mode. The combustion chamber comprises an upper vortex chamber with an arc-shaped necking, and a lower vortex chamber with an arc-shaped necking. A dividing ridge is arranged between the upper vortex chamber and the lower vortex chamber, a dome frustum is arranged at the center of the combustion chamber, the dividing ridge of the upper vortex chamber and the lower vortex chamber and the upper vortex chamber are provided with flow guide inclined planes, and the upper vortex chamber and the top of the piston are provided with curved surfaces. The design is suitable for a supercharged and intercooled direct injection diesel engine. The invention can organize and utilize the horizontal vortex and the longitudinal tumble around the center line of the cylinder to improve the fuel-air mixing, so that the mixed gas is uniform and is fully combusted, a local high-temperature area is reduced, and the discharge amount of NOx and SOOT is reduced. Can also be formed in the upper vortex chamber by the flywheel effect: the circular arc type necking structure of the upper vortex chamber can form a vortex with the maximum linear velocity in the whole combustion chamber, and the duration time is from the later stage of a compression stroke to the early-middle stage of an expansion stroke. The upper swirl chamber stores fresh air during the compression stroke, providing air for the oxidation of the post combustion SOOT.
Description
Technical Field
The invention relates to the field of small and medium-sized supercharged intercooling direct injection diesel engines, in particular to a high-low double-vortex chamber double-throat combustion chamber.
Background
The 'oil-gas-chamber' matching in the diesel engine directly influences the generation of mixed gas, and further directly concerns the dynamic property and the emission property of the diesel engine. The shape of the combustion chamber is the basic carrier of the "oil-gas-chamber" match, determining the upper limit of the degree of match.
At present, most direct injection diesel engines adopt deep pits
The type necking combustion chamber forms extrusion flow and reverse extrusion flow at a necking position before and after a compression top dead center. Oblique axis swirl is formed when squish flow interacts with horizontal swirl in the combustion chamber. Although this is advantageous for atomization, evaporation, and air mixing of fuel, the supercharged diesel engine has a short penetration distance, and it is difficult to use the swirl flow and air at the bottom of the combustion chamber. This results in the commonalities
The type of throat combustor has high NOx and SOOT (SOOT) emissions.
The current double-layer flow-dividing combustion technology can divide fuel, increase the penetration distance of oil injection, guide the fuel and combust the fuel in layers. This widens the combustion range, lowers the in-cylinder average temperature, and reduces the generation of NOx, but due to wall impingement, a large amount of SOOT will be generated on the wall surface. The common double-layer flow-splitting combustion technology focuses on horizontal vortex flow rather than longitudinal tumble flow.
Disclosure of Invention
The invention aims to disclose a bias type flow dividing combustion chamber which can improve oil-gas mixing by using longitudinal tumble flow and horizontal vortex flow in a lasting and efficient mode, thereby improving power and reducing harmful substance emission.
The purpose realization method of the invention is as follows:
the combustion chamber is divided into two vortex chambers arranged in high and low directions, the upper vortex chamber is in a ring shape, the reducing opening is in a circular arc shape, and the lower vortex chamber is as common as the common vortex chamber
The bottom of the necking combustion chamber is also in a circular arc shape. In supercharged diesel engines with a short penetration distance, the main part of the combustion takes place in the upper part of the combustion chamber. The lower vortex chamber has low air utilization rate and less turbulent kinetic energy, so that the present invention improves oil-gas mixture via increasing the total air amount and turbulent kinetic energy in the upper vortex chamber.
On the compression stroke, due to the special configuration of the upper swirl chamber, a longitudinally rotating tumble flow will be formed near the compression top dead center. Because the upper vortex chamber is a circular arc-shaped necking, and is far away from the central line of the combustion chamber compared with the lower vortex chamber, and because of the reasons of supercharging middle-cooling spiral air intake and combustion chamber offset, the upper vortex chamber forms the vortex with the maximum linear speed in the whole combustion chamber, and because of the action of centrifugal force, the rolling flow rotating longitudinally in the upper vortex chamber also rotates along with the central line of the crankshaft, so that the rolling flow rotating longitudinally becomes permanent. The annular configuration of the upper vortex chamber also maintains the maximum horizontal rotational velocity in the cylinder in the middle and late stages of the compression stroke and throughout the combustion period.
In addition, the upper vortex chamber can hold fresh air rotating at high speed during the compression stroke, which is beneficial to the quick and uniform mixing of oil and gas. Meanwhile, the existence of a larger upper vortex chamber causes the space at the upper part of the combustion chamber to be enlarged and the total amount of air to be increased. Since the main part of the combustion takes place in the upper part of the combustion chamber, this contributes to reducing the average temperature in the upper part of the combustion chamber, thereby reducing the production of NOx. When the afterburning period is reached, the SOOT generated in the flash combustion period is oxidized by the air rotating at high speed in the upper vortex chamber, and the afterburning period is improved. This achieves the SOOT emission reduction objective. The circular arc-shaped necking of the upper vortex chamber can also reduce fuel entering the clearance volume, and the insufficient combustion caused by the clearance effect at the top dead center of compression is reduced.
The invention realizes the staged combustion to a certain extent due to the fact that the boundary ridge of the upper vortex chamber and the lower vortex chamber has fuel guiding property.
The distance between the central line of the arc top frustum and the central line of the combustion chamber is the offset of the combustion chamber. The offset can enhance the horizontal rotational speed of the vortex.
The invention has the beneficial effects that: the combustion chamber not only can form permanent longitudinal tumble and horizontal vortex with larger linear velocity in the upper vortex chamber, but also can form a flywheel effect: air is stored during the compression period to provide oxygen for the post-combustion period. The aim of simultaneously reducing NOx and SOOT can be achieved by matching a proper fuel injection included angle.
Description of the drawings:
FIG. 1 is a constructional view of the present invention;
FIG. 2a is a schematic longitudinal vortex diagram of a high-low type double-vortex double-throat combustor;
FIG. 2b is a schematic view of longitudinal swirl of a split-flow single-throat combustor;
FIG. 2c is a schematic view of the longitudinal vortex of the combustion chamber of the large vortex chamber;
FIG. 2d is a general scheme
Longitudinal vortex schematic diagram of the combustion chamber;
FIG. 3 is a horizontal velocity profile of the present invention and three conventional combustors before and after fuel injection;
FIG. 4 is a comparison of oxygen mass distribution for the present invention at 20 ATDC versus three conventional combustors;
FIG. 5 is a cylinder pressure diagram of the present invention with three other conventional combustion chambers;
FIG. 6 is a comparison of the present invention with three other common combustor NOx emissions;
FIG. 7 is a comparison of the present invention with the other three common combustor SOOT emissions;
FIG. 8 shows the NOx emission characteristics of the present invention when the radius ratio of the upper and lower swirl chambers is different;
FIG. 9 shows the SOOT discharge characteristics of the present invention when the ratio of the upper and lower vortex chamber radii is different.
Wherein: 1-upper vortex chamber top curved surface; 2-upper vortex chamber; 3-a flow guiding inclined plane; 4-upper and lower vortex chamber boundary ridge; 5-lower vortex chamber; 6-dome frustum.
Detailed Description
The basic idea of the invention is to design the offset combustion chamber into two vortex chambers with high and low distribution, and to utilize the circular arc-shaped necking of the upper vortex chamber to strengthen the tumble and vortex in the combustion chamber, so that the oil and gas can be mixed quickly and uniformly. And the SOOT emissions are reduced by utilizing the "flywheel effect" of the upper vortex chamber to provide oxygen for the post combustion period. Meanwhile, the upper and lower vortex chamber boundary ridges can realize the split combustion of part of fuel.
The invention is further described below with reference to the accompanying drawings:
the first embodiment is as follows:
as shown in fig. 1: a high-low double-vortex chamber double-throat combustion chamber is characterized in that a longitudinal section of the combustion chamber is butterfly-shaped, the combustion chamber is divided into two arc-shaped throat vortex chambers which are distributed up and down, and the center of the combustion chamber is an arc-top circular table.
The combustion chamber is offset by 4 mm.
The radius ratio R/R of the circular arc necking of the upper vortex chamber and the lower vortex chamber is 0.3.
A boundary ridge is arranged between the upper vortex chamber and the lower vortex chamber, and the diameter of a top fillet of the boundary ridge is 4 mm.
A section of flow guide inclined plane is arranged between the upper vortex chamber and the boundary ridge, and the flow guide inclined plane is tangent to the arc of the upper vortex chamber.
An upper vortex chamber top curved surface is arranged between the upper vortex chamber and the top of the piston, and the top end is a round angle with the diameter of 3 mm; the fillet is lower than the top of the piston.
The diameter-depth ratio L/D of the combustion chamber is 3.0.
The second embodiment is as follows:
as shown in fig. 1: a high-low double-vortex chamber double-throat combustion chamber is characterized in that a longitudinal section of the combustion chamber is butterfly-shaped, the combustion chamber is divided into two arc-shaped throat vortex chambers which are distributed up and down, and the center of the combustion chamber is an arc-top circular table.
The combustion chamber is offset by 5 mm.
The radius ratio R/R of the circular arc necking of the upper vortex chamber and the lower vortex chamber is 1.3.
A boundary ridge is arranged between the upper vortex chamber and the lower vortex chamber, and the diameter of a top fillet of the boundary ridge is 2 mm.
A section of flow guide inclined plane is arranged between the upper vortex chamber and the boundary ridge, and the flow guide inclined plane is tangent to the arc of the upper vortex chamber.
An upper vortex chamber top curved surface is arranged between the upper vortex chamber and the top of the piston, and the diameter of a top fillet is 2 mm; the fillet is lower than the top of the piston.
The diameter-depth ratio L/D of the combustion chamber is 3.2.
The third embodiment is as follows:
the difference from the first embodiment is that the circular arc necking radius ratio R/R of the upper vortex chamber and the lower vortex chamber is 0.7.
The fourth embodiment:
the difference from the first embodiment is that the circular arc necking radius ratio R/R of the upper vortex chamber and the lower vortex chamber is 1.
FIG. 2 is a longitudinal velocity field of the present invention and several conventional direct injection combustors before top dead center. The high-low type double-vortex double-throat combustion chamber in the invention can form the largest longitudinal vortex (continuously rotating tumble flow), which is related to the circular-arc throat diameter of the upper vortex chamber. The conventional combustion chamber has strong squish flow but fails to form a significant longitudinal vortex (tumble flow with continuous rotation). Although longitudinal vortexes (continuously rotating tumble flows) are formed in the other two combustion chambers, the time is not long, and the duration of the longitudinal vortexes (continuously rotating tumble flows) formed in the upper vortex chamber of the high-low type double-vortex double-throat combustion chamber is longest through calculation.
FIG. 3 is a horizontal velocity profile of the present invention compared to several conventional direct injection combustion chambers before and after injection. The fuel injection start-stop angle adopted by the calculation is 12 degrees BTDC and 8 degrees ATDC. When the fuel injection is started, namely 12 degrees BTDC, the throat outlets of the high-low type double-vortex double-throat combustion chamber and the other three common direct injection combustion chambers of the invention all have vortexes which rotate around the central line of the combustion chamber at high speed. At the end of the oil injection, namely 8 degrees ATDC, the upper vortex chamber of the high-low type double-vortex double-throat combustion chamber still has extremely high vortex speed. While the remaining combustion chambers are already at the clearance volume position where the swirl velocity is maximum. Before and during oil spout, the vortex of high-speed rotation makes oil-gas mixture more rapidly and even, and this can optimize the burning, reduces the generation of harmful substance and raises the power. When the crank angle is 20 degrees ATDC in the post-combustion period, the upper vortex chamber of the high-low type double-vortex double-throat combustion chamber still keeps higher rotation speed. This can provide power for oxygen supply during the post-combustion period and average in-cylinder temperatures. Thereby shortening the post-combustion period and reducing the emission of harmful substances.
FIG. 4 is a comparison of the oxygen mass distribution of the "high-low dual-swirl dual-throat combustor" of the present invention with several conventional combustors at a crank angle of 20 ATDC, which reduces the space at the bottom that is difficult to use and relatively increases the total oxygen in the upper portion of the combustor for the same combustor volume. The upper oxygen-deficient range in the high-low type double-vortex double-throat combustion chamber is the minimum, a large amount of oxygen is also held in the upper vortex chamber, and oxygen is continuously exchanged with an oxygen-enriched area, so that conditions are provided for SOOT oxidation in a post-combustion period.
FIG. 5 is a simulated cylinder pressure diagram of four combustion chambers, it can be seen that the pressure peak point of the bottom large vortex combustion chamber is the lowest, and the in-cylinder pressures of the high-low type double vortex double-necking combustion chamber and the common split-flow combustion chamber are all higher than the in-cylinder pressure of the common split-flow combustion chamber
The profile combustion chamber is high, which also demonstrates that the "flywheel effect" of the upper swirl chamber can improve the air-fuel mixture and thus increase the power.
FIGS. 6 and 7 are NOx and SOOT emissions comparisons for a high-low dual-swirl dual-throat combustor with other combustors according to the present invention. The high-low type double-vortex double-throat combustion chamber simultaneously shows the lowest NOx and SOOT emission, and as can be known by combining the graph 5, the high-low type double-vortex double-throat combustion chamber not only can improve the power, but also can achieve the purpose of emission reduction under proper conditions.
Fig. 8 and 9 show the NOx and SOOT emission characteristics of the high-low type double vortex double-throat combustor of the present invention at different ratio of the radius of the high-low vortex chamber, which is better when R/R =0.7 and R/R = 1.0.
Claims (9)
1. A high-low double-vortex chamber double-throat combustion chamber is characterized in that a longitudinal section of the combustion chamber is butterfly-shaped, the combustion chamber is divided into two arc-shaped throat vortex chambers which are distributed in a high-low mode, and an arc-top circular table is arranged in the center of the combustion chamber.
2. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein the combustion chamber is offset by 4-5 mm.
3. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein the circular arc throat radius ratio R/R of the upper vortex chamber and the lower vortex chamber is 0.3-1.3.
4. The dual-vortex chamber dual-throat combustion chamber as claimed in claim 1, wherein a boundary ridge is provided between the upper and lower vortex chambers, and the top of the boundary ridge is rounded.
5. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1 or 4, wherein a section of flow guide inclined plane is arranged between the upper vortex chamber and the boundary ridge, and the flow guide inclined plane is tangent to the upper vortex chamber.
6. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein an upper vortex chamber top curved surface is arranged between the upper vortex chamber and the top of the piston, and the top end of the upper vortex chamber is provided with a fillet; the fillet is slightly lower than the top of the piston.
7. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein the diameter-depth ratio of the combustion chamber is 3-3.2.
8. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein the circular arc throat radius ratio R/R of the upper vortex chamber and the lower vortex chamber is 0.3.
9. The high-low type double vortex chamber double-throat combustion chamber as claimed in claim 1, wherein the circular arc throat radius ratio R/R of the upper vortex chamber and the lower vortex chamber is 1.3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010542285.7A CN111648876A (en) | 2020-06-15 | 2020-06-15 | High-low type double vortex chamber double-reducing combustion chamber |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010542285.7A CN111648876A (en) | 2020-06-15 | 2020-06-15 | High-low type double vortex chamber double-reducing combustion chamber |
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| CN111648876A true CN111648876A (en) | 2020-09-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010542285.7A Pending CN111648876A (en) | 2020-06-15 | 2020-06-15 | High-low type double vortex chamber double-reducing combustion chamber |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115163293A (en) * | 2022-06-30 | 2022-10-11 | 北京理工大学 | Tumble-squeeze-swirl synergistic rapid combustion optimization method for natural gas engine |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1040851A (en) * | 1988-08-31 | 1990-03-28 | 北京理工大学 | Combustion system with double plume |
| CN205663527U (en) * | 2016-06-14 | 2016-10-26 | 广西玉柴机器股份有限公司 | Combustion chamber of interior soot of diesel engine cylinder reduces |
| CN106285927A (en) * | 2016-09-26 | 2017-01-04 | 江苏大学 | A kind of concave-concave pit type chamber structure for rotary engine |
-
2020
- 2020-06-15 CN CN202010542285.7A patent/CN111648876A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1040851A (en) * | 1988-08-31 | 1990-03-28 | 北京理工大学 | Combustion system with double plume |
| CN205663527U (en) * | 2016-06-14 | 2016-10-26 | 广西玉柴机器股份有限公司 | Combustion chamber of interior soot of diesel engine cylinder reduces |
| CN106285927A (en) * | 2016-09-26 | 2017-01-04 | 江苏大学 | A kind of concave-concave pit type chamber structure for rotary engine |
Non-Patent Citations (2)
| Title |
|---|
| 刘金武: "燃烧室偏置对直喷汽油机NOx生成影响的数值研究", 《中国工程热物理学会第十一届年会论文集 燃烧学上》 * |
| 卢泓坤: "基于响应面法的柴油机分区燃烧系统多参数多目标优化研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115163293A (en) * | 2022-06-30 | 2022-10-11 | 北京理工大学 | Tumble-squeeze-swirl synergistic rapid combustion optimization method for natural gas engine |
| CN115163293B (en) * | 2022-06-30 | 2023-08-18 | 北京理工大学 | Rolling flow-extrusion flow-rolling flow synergistic rapid combustion optimization method for natural gas engine |
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Application publication date: 20200911 |