Gas Engine Nozzle Hole Curvature for Combustion Stability
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Solution Overview
Problem
In spark ignition precombustion-chamber type gas engines, unstable gas flow through the nozzle hole leads to inconsistent mixed gas density around the ignition plug, affecting combustion stability, and existing designs lack detailed specifications for nozzle hole shape, such as inner diameter and length.
Innovation Solution
The nozzle hole features a curved surface along its periphery and a throat that extends linearly, with specific ratios of length to diameter, stabilizing gas flow by suppressing turbulence and ensuring proper mixing for consistent combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the nozzle hole shape is not optimized, then the structure is simple, but the mixed gas flow becomes unstable and combustion varies
Solution Approach 1:
The patent applies parameter changes by specifying precise dimensional ratios for the nozzle hole: the curved surface radius R1 is 0.5-2.0 times the throat diameter d1, and the curved surface length L1 is 0.5-2.0 times the throat length L2. These parameter optimizations stabilize mixed gas flow and improve combustion reliability without significantly increasing structural complexity
Solution Approach 2:
The patent applies spheroidality by incorporating a curved surface portion in the nozzle hole with specific radius R1. This curvature modifies the flow characteristics of mixed gas entering the precombustion chamber, preventing flow separation and turbulence while maintaining a relatively simple overall structure
2Productivity
If the nozzle hole inner diameter is large, then gas flow rate is high, but flow stability decreases and turbulence increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the relationship between nozzle hole dimensions and flow characteristics. The curved surface radius R1 and length L1 are specifically proportioned to the throat diameter d1 and length L2, creating optimal flow conditions that maintain stability even at adequate flow rates
Solution Approach 2:
The curved surface portion acts as an intermediary element between the nozzle hole and the precombustion chamber. It serves as a transition zone that smooths flow entry, preventing direct turbulence while maintaining sufficient gas flow rate for effective combustion
3Volume of moving object
If the throat length to diameter ratio is small, then the structure is compact, but turbulence occurs in mixed gas flow
Solution Approach 1:
The patent applies parameter changes by optimizing the throat geometry with specific ratios: the curved surface length L1 is 0.5-2.0 times the throat length L2, and the curved surface radius R1 is 0.5-2.0 times the throat diameter d1. These proportions ensure stable flow without requiring excessive throat length, maintaining compact chamber volume
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design stabilizes gas flow and combustion by maintaining a suitable mixed gas density around the ignition plug, reducing combustion variation and eliminating the need to adjust the ignition plug position.
Implementation Method 1
the curved surface portion is formed along the periphery of the throat-side opening edge portion of the nozzle hole, and thus it is possible to suppress rapid diffusion of mixed gas when mixed gas is discharged from the nozzle hole into the throat
Implementation Method 2
as the mixed gas in the precombustion chamber is ignited at a predetermined timing with an ignition plug disposed in the precombustion chamber
Implementation Method 3
the mixed gas in the precombustion chamber is combusted, and combustion flame is injected into the cylinder through the precombustion chamber nozzle hole. Due to such injection of combustion flame, the lean mixed gas inside the cylinder is ignited, and is eventually combusted
Data Source
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AI summary
Provided is a gas engine configured such that an auxiliary chamber, in which a spark plug is provided at a top part of the auxiliary chamber and an injection hole is provided in a throat formed at a bottom part of the auxiliary chamber, is provided in a main combustion chamber, and during compression, a mixed gas flows from the main combustion chamber into the throat of the auxiliary chamber via the injection hole. A curved surface part is formed along the peripheral edge of an opening end at the throat side of the injection hole, and the throat extends linearly along the central axis of the auxiliary chamber. The ratio of the length of the throat relative to the inner diameter of the throat is from 1.6 to 2.6, and a value obtained by multiplying the ratio of the inner diameter of the throat relative to the radius of the curved surface part by the ratio of the throat diameter relative to the diameter of the top part of the auxiliary chamber is 18 or more.