Fuel Injector Port Geometry for Flow Separation Control
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Solution Overview
Problem
Fuel injectors in internal combustion engines experience fuel flow separation at injection ports, leading to incomplete combustion and unburned particle formation due to fuel droplets adhering to the injector tip.
Innovation Solution
The fuel injector is designed with injection ports on concentric circles, where the first injection port has its center on a smaller circle and the second on a larger circle opposite the tangent of the first, with edges forming obtuse angles on non-opposing sides, reducing fuel flow separation by balancing fuel flow between ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is injected through conventional injection ports, then fuel injection function is achieved, but fuel flow separation occurs causing incomplete combustion and unburned particles
Solution Approach 1:
The injection ports are designed with different geometric configurations (acute angles at upstream edges, obtuse angles at downstream edges) to create locally optimized flow conditions. This local quality variation prevents flow separation at critical locations while maintaining effective fuel injection, thereby reducing unburned particles and improving combustion completeness
Solution Approach 2:
The injection ports employ asymmetric geometry where the upstream edge forms an acute angle and the downstream edge forms an obtuse angle. This asymmetric design creates favorable pressure gradients that prevent flow separation, unlike symmetric designs that may cause adverse pressure gradients and separation. The asymmetric configuration directly addresses the flow separation problem while maintaining injection effectiveness
2Reliability
If injection ports are positioned on a single circle, then manufacturing is simplified, but fuel flow imbalance and separation occur
Solution Approach 1:
The injection ports are arranged on two different circles (first circle with smaller radius, second circle with larger radius) rather than a single circle. This dimensional change in the radial direction allows for better fuel flow distribution and balance across the injector, preventing flow separation while managing the increased geometric complexity through systematic circular patterning
Data Source
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AI summary
The present invention provides a fuel injector capable of suppressing separation of a fuel flow in an injection port during fuel injection. A fuel injector (30) includes plural injection ports (31a to 31f), each of which injects the fuel into an internal combustion engine (10). The plural injection ports (31a to 31f) are provided in plural on a first circle with a first radius (R1) and on a second circle with a larger second radius (R2) than the first radius (R1), and includes: a first injection port (31a), a center of an opening of which is provided on the first circle; and a second injection port (31c), a center of an opening of which is provided on the second circle on an opposite side of a tangent of the first circle, which passes the center of the opening of the first injection port, from a center axis (CF1) of the fuel injector (30). When seen in a cross section on the shortest line connecting the center of the first injection port (31a) and the center of the second injection port (31c), a first angle (θ1) defined by a center axis (CF2) of the first injection port (31a) and the center axis (CF1) of the fuel injector (30) is larger than a second angle (θ2) defined by a center axis (CF3) of the second injection port (31c) and the center axis (CF1) of the fuel injector (30).