Air Inlet Nozzle Flow Control Elements to Reduce Gas Heater Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional air inlet nozzles for gas heaters often suffer from noise emissions due to flow separations and flow-induced vibrations, which increase noise levels, especially at certain operating points, despite the use of silencers to reduce aerodynamic noise.
Innovation Solution
An air inlet nozzle with a hollow body and exposed flow influencing elements, such as baffles, slats, or notches, designed to reduce aerodynamic noise by preventing undesirable flow separations and promoting targeted air flow direction, thereby minimizing noise emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional air inlet nozzle with a smooth edge is used, then the structure is simple and easy to manufacture, but flow separation occurs at the edge which generates noise emissions and causes flow-induced vibration
Solution Approach 1:
The invention applies local quality by modifying only the edge region of the air inlet nozzle with flow-influencing elements (such as rounded edges, chamfers, or small protrusions), while keeping the rest of the nozzle structure simple and easy to manufacture. This localized modification prevents flow separation and reduces noise emissions without complicating the overall manufacturing process.
Solution Approach 2:
The invention converts the harmful sharp edge that causes flow separation into a beneficial rounded or modified edge structure. By intentionally designing the edge with flow-influencing elements, the previously harmful flow separation is eliminated, transforming the edge geometry from a noise-generating feature into a noise-reducing feature.
2Weight of moving object
If the silencer has low weight, then it is easier to manufacture and install, but flow-induced vibration excitation occurs due to low mass, radiating additional secondary airborne noise
Solution Approach 1:
The invention applies preliminary action by preventing flow separation at the air inlet nozzle edge before the air flow reaches the silencer. By modifying the nozzle edge geometry in advance, the air flow remains attached and stable, preventing the excitation of flow-induced vibrations in the lightweight silencer structure before it can radiate secondary noise.
3Manufacturing precision
If the air inlet opening has a sharp edge, then the geometry is simple and precise, but flow separation occurs at the edge generating noise emissions
Solution Approach 1:
The invention applies local quality by modifying only the critical edge region of the air inlet opening with flow-influencing elements, while maintaining precise manufacturing tolerances for the overall opening geometry. The local modification addresses flow separation without compromising the precision requirements of the air inlet opening.
Solution Approach 2:
The invention applies spheroidality by rounding the sharp edge of the air inlet opening or adding curved flow-influencing elements. This curvature modification eliminates the sharp edge that causes flow separation, reducing noise emissions while maintaining manufacturing precision through controlled radii of curvature.
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 use of these flow influencing elements significantly reduces noise levels, as demonstrated by lower measured loudness in various embodiments compared to conventional nozzles, effectively addressing the issue of noise emissions and flow-induced vibrations.
Implementation Method 1
flow separation can occur at the edge, which can generate noise emissions
Implementation Method 2
flow-induced vibration excitation may also occur at the silencer due to its low weight
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Air inlet nozzle (1) for a gas heating appliance (28), comprising a hollow body (26) with at least one air inlet opening (2) which is surrounded by a mouth edge (4) which partially covers the hollow body (26), wherein the mouth edge (4) is provided with several exposed flow control elements (5, 6, 7, 16).