Exhaust Diffuser with Coanda Flaps for Gas Cooling
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Solution Overview
Problem
Existing exhaust pipe diffusers are inadequate in mixing cooling air with hot exhaust gas core streams, leading to hazardous high exit temperatures due to the lack of optimal diffusion, especially in systems with regeneration cycles.
Innovation Solution
A flow diffuser with inner diffusion ports and extension flaps is designed to attach to the exhaust pipe, creating outer diffusion ports and utilizing the Coandă Effect to promote turbulence and mixing of hot exhaust gas with ambient air, reducing temperature and velocity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If prior art exhaust pipe diffusers are used, then the structure is simple, but the mixing of cooling air with hot exhaust gas core streams is inadequate, resulting in hazardous high exit temperatures
Solution Approach 1:
The diffuser body is segmented into multiple functional zones: an annular region with outer diffusion ports, a central region with inner diffusion ports, and extension flaps. This segmentation allows simultaneous creation of multiple flow paths for cooling air and exhaust gas, enabling effective mixing while maintaining a relatively simple overall structure.
Solution Approach 2:
The diffuser body acts as an intermediary structure between the exhaust pipe and the environment. It introduces cooling air through outer diffusion ports and mixes it with hot exhaust gas through turbulence promotion, thereby mediating the temperature reduction from 900K to 600K without requiring complex active cooling systems.
2Temperature
If the body cross-sectional area is reduced to create outer diffusion ports, then cooling air mixing is improved, but the available area for exhaust gas flow is reduced
Solution Approach 1:
The solution transitions from a single-plane diffusion approach to a multi-dimensional flow structure. Extension flaps extend in the axial direction, and diffusion ports are distributed both radially (outer ports in annular region, inner ports in central region) and axially, creating three-dimensional flow paths that maximize mixing efficiency without excessively reducing the body cross-sectional area.
Solution Approach 2:
The diffuser body is divided into functional regions: an annular region containing outer diffusion ports for cooling air intake, and a central region with inner diffusion ports for exhaust gas flow. This segmentation allows simultaneous optimization of cooling air mixing and exhaust gas flow area.
3Productivity
If extension flaps are added to promote turbulence and mixing, then temperature reduction efficiency is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Extension flaps are positioned at specific angles relative to the axial direction, creating curved flow paths that naturally promote turbulence and mixing. This geometric approach to inducing turbulence is more manufacturable than complex active turbulence generators while achieving the desired mixing efficiency for rapid heat dissipation.
4Reliability
If multiple diffusion ports are created, then the diffusion and mixing effectiveness is improved, but the manufacturing precision requirements increase
Solution Approach 1:
Diffusion ports are segmented into two distinct groups: outer diffusion ports located in the annular region and inner diffusion ports located in the central region. This spatial segmentation simplifies the positioning requirements compared to a fully distributed array, as each group can be manufactured and positioned independently with standard tolerances while maintaining effective mixing.
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 flow diffuser effectively reduces exhaust gas temperatures from over 900 degrees Kelvin to around 600 degrees Kelvin within a shorter distance, enhancing heat dissipation and safety by improving fluid mixing and diffusion.
Implementation Method 1
utilizing the Coandă Effect to promote turbulence and mixing of hot exhaust gas with ambient air
Implementation Method 2
promote turbulence in the exhaust stream for fluid mixing and heat dissipation
Implementation Method 3
enhancing heat dissipation and safety by improving fluid mixing and diffusion
Data Source
AI summary
A flow diffuser for vehicles of the type having an engine and an exhaust pipe generally includes a body including a plurality of inner diffusion ports extending through the body, wherein the body may be attached to an exhaust pipe at or near the exit plane of the exhaust pipe, wherein the body is sized to have a cross-sectional area that is smaller than the cross-sectional area of the exit plane of the exhaust pipe to create a plurality of outer diffusion ports around at least a portion of the outer perimeter of the body when coupled to the exhaust pipe, and one or more extension flaps extending from at least a portion of the outer perimeter of the body.