Crowned Inlet Baffle for Exhaust Mixer
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Solution Overview
Problem
Compact mixer configurations in exhaust systems face challenges in maintaining high mixing performance while ensuring durability to withstand vehicle and road vibrations, given the limited packaging space.
Innovation Solution
A mixer assembly with a crowned inlet baffle that redirects bypass flow to increase the open area within the internal cavity, enhancing mixing performance and durability by strategically positioning the crowned portion and embossment to accommodate increased flow and reduce vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a compact mixer configuration is used to reduce overall length for efficient packaging, then packaging efficiency is improved, but mixing performance and durability may deteriorate
Solution Approach 1:
The inlet baffle includes a crowned portion that curves away from the reactor, creating a curved surface geometry instead of a flat plane. This curvature increases the open area within the internal cavity between the inlet baffle and reactor, allowing for improved flow distribution and mixing performance while maintaining the compact overall length of the mixer assembly
2Length of moving object
If the inlet baffle is positioned closer to the reactor to reduce length, then packaging efficiency is improved, but flow distribution and mixing performance worsen
Solution Approach 1:
The crowned portion on the inlet baffle creates a curved surface that maximizes the open area within the constrained space between the inlet baffle and reactor. This curved geometry optimizes flow distribution and enhances mixing performance despite the reduced distance between components
3Ease of manufacture
If a flat inlet baffle design is used for simplicity, then manufacturing ease is improved, but structural durability against vibrations worsens
Solution Approach 1:
The crowned portion introduces a curved surface to the inlet baffle design. This curvature provides structural reinforcement that enhances durability and resistance to vehicle and road vibrations, while still being manufacturable using standard forming processes
4Productivity
If the open area between inlet baffle and reactor is increased to improve flow distribution, then mixing performance is improved, but the overall length of the mixer increases
Solution Approach 1:
The crowned portion creates a curved surface that efficiently utilizes the available radial space, increasing the open area between the inlet baffle and reactor without extending the axial length of the mixer. This allows for improved flow distribution and mixing performance within the compact configuration
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 achieves a 25% increase in flow efficiency and improved durability by allowing for a more uniform mixture with reduced backpressure in the shortest overall mixer length, as indicated by Computational Fluid Dynamic results.
Implementation Method 1
The inlet baffle includes a crowned portion that curves away from the reactor to provide for an increased open area within the internal cavity between the inlet baffle and the reactor
Implementation Method 2
an embossment is formed within a portion of the crowned portion, the embossment protruding outwardly and away from an upstream surface of the crowned portion to further increase the open area within the internal cavity
Data Source
AI summary
A mixer assembly for a vehicle exhaust system includes a mixer shell defining an internal cavity, wherein the mixer shell includes an upstream end configured to receive exhaust gases and downstream end, and a reactor positioned within the internal cavity. The reactor has a reactor inlet configured to receive injected fluid and a reactor outlet that directs a mixture of exhaust gas and injected fluid into the internal cavity. An inlet baffle is mounted to the upstream end of the mixer shell. The inlet baffle includes at least one opening that directs exhaust gas into at least one exhaust gas inlet to the reactor and a plurality of bypass openings that direct exhaust gas to bypass entry into the reactor. The inlet baffle includes a crowned portion that curves away from the reactor to provide for an increased open area within the internal cavity between the inlet baffle and the reactor.