Annular Expansion Ring Airflow Redirection for Fuel Injector Coke Prevention
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Solution Overview
Problem
Existing fuel injection systems suffer from coke deposits on the injector and venturi due to turbulent air flow, which degrades fuel atomization and increases the risk of flameout at low engine speeds.
Innovation Solution
An annular expansion ring with a conical slot converging downstream and holes that redirect air to impact the inner wall of the slot, ensuring a homogeneous air flow that avoids direct impact on the injector and venturi, reducing turbulence and coke deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If air is introduced through holes in the expansion ring to prevent coke deposits, then coke deposition on the injector is reduced, but turbulence is created that causes coke deposits on the venturi and degrades fuel atomization
Solution Approach 1:
The patent changes the orientation parameter of the air holes from axial (parallel to main axis) to radial (perpendicular to main axis). This parameter change redirects the air flow from impacting the injector downstream end to impacting the inner wall of the radial slot, thereby preventing coke deposits on the injector while avoiding turbulence that would affect the venturi and fuel atomization
Solution Approach 2:
The patent introduces a radial dimension to the air hole orientation, changing the air flow direction from axial to radial. The air holes are oriented at an angle of 90±10 degrees relative to the main axis, directing air flow perpendicular to the main axis and into the radial slot, which eliminates the harmful turbulence in the axial direction while maintaining the protective air film
2Reliability
If axial air flow is used to protect the injector, then coke deposits on the injector are prevented, but the air flow directly impacts the venturi and primary swirl causing combustion instability at low speeds
Solution Approach 1:
The patent changes the flow direction parameter from axial to radial by orienting holes perpendicular to the main axis. This redirects air flow away from the venturi and primary swirl components, eliminating combustion instability at low speeds while maintaining injector protection through the radial slot configuration
Solution Approach 2:
The radial slot acts as an intermediary structure that receives air from the radially oriented holes and redirects it along the radial path. This intermediary configuration prevents direct air impact on the venturi and primary swirl, allowing low-speed combustion operation while maintaining injector protection
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
The solution prevents coke deposits on the injector and venturi, allowing for lower fuel injection rates and improved combustion chamber operation at low speeds, reducing the risk of flameout and maintaining efficient fuel atomization.
Implementation Method 1
forms a layer or film of air around the injector, which prevents coke from depositing on the downstream end of the injector
Implementation Method 2
the air coming from the holes enters the zone downstream of the injector by creating turbulence
Data Source
Figure 1~3
Figure 4~5
AI summary
An annular expansion ring (20) centered on a main axis (A) and adapted to be mounted on a coaxial fuel injector (10). This ring has holes (26) distributed around this main axis, opening onto its upstream face, and allowing air to pass to the area downstream of this ring. This ring (20) has a conical annular slot (30) converging downstream, open downstream, the holes (26) opening into the upstream part of the annular slot (30). The axis of each of these holes (26) makes an angle with the main axis (A) strictly greater than the angle made with this main axis by the generatrix of the cone defining the annular slot (30), such that the air exiting the holes (26) impacts the inner wall (38) of the annular slot that is closest to the main axis.