Axial Fan Outlet Guide Struts with Radial NACA Profile Variation
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Solution Overview
Problem
Existing guide devices for axial fans in the commercial vehicle sector face inefficiencies and increased noise levels due to suboptimal design, particularly in how they influence the flow generated by the impeller, leading to higher outlet losses and reduced aerodynamic efficiency.
Innovation Solution
A guide device with guide struts designed using NACA profiles, varying parameters such as camber, thickness, and angle of attack along the radial direction to delay dynamic pressure conversion into static pressure, reducing outlet losses and noise, while maintaining air performance across the characteristic curve range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional guide devices are used, then the axial fan can generate volume flow, but the outlet losses are high and aerodynamic efficiency is reduced
Solution Approach 1:
The guide struts are designed with varying geometric parameters (camber, thickness, angle of attack) along their radial extension, creating local quality variations that optimize flow guidance at different radial positions. This allows the guide device to adapt to the varying flow conditions across the impeller outlet, reducing outlet losses while maintaining high aerodynamic efficiency throughout the characteristic curve range
Solution Approach 2:
The invention applies systematic parameter changes to the guide strut profiles, using NACA profile geometry with varying camber (f), camber allowance (x f), thickness (d), thickness allowance (x d), angle of attack (α), and extension (L ax,N) along the radial direction. These parameter variations are specifically designed to delay dynamic pressure conversion and reduce outlet losses across the entire operating range
2Object-affected harmful factors
If conventional guide devices are used, then the axial fan operates, but noise development is increased
Solution Approach 1:
The guide struts feature locally optimized geometry with varying camber and thickness distributions along the radial direction, creating smooth flow guidance that reduces turbulence and noise generation. The local quality variations ensure optimal flow control at each radial position while maintaining overall air performance
Solution Approach 2:
The NACA profile geometry of the guide struts incorporates curved surfaces and smooth transitions, particularly in the cambered profile shape. This curvature design promotes smooth flow attachment and reduces flow separation, thereby decreasing turbulence-induced noise while preserving aerodynamic efficiency
3Productivity
If guide strut parameters are varied along radial direction, then efficiency increases, but device complexity increases
Solution Approach 1:
The invention systematically varies geometric parameters (camber, thickness, angle of attack) along the radial direction of the guide struts, creating an optimized profile distribution that enhances static aerodynamic efficiency. The parameter variations follow specific functional relationships that can be mathematically defined and manufactured
Solution Approach 2:
The guide device is divided into multiple guide struts, each independently optimized with its own NACA profile geometry. This segmentation allows each strut to be designed and manufactured separately with precise geometric control, managing complexity through modular design while achieving high overall efficiency
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 significantly enhances the static aerodynamic efficiency and reduces sound power levels of axial fans by optimizing the profile of guide struts, achieving improved performance and noise reduction.
Implementation Method 1
the dynamic pressure component in the swirling flow generated by the impeller of the axial fan is delayed after the impeller of the velocity vector is partially converted into static pressure
Data Source
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AI summary
The invention relates to an outlet guide device configured for arranging in an outflow-side flow of an impeller of an axial fan (1), wherein the outlet guide device has a multiplicity of outlet guide struts (6), wherein each of the outlet guide struts (6) is configured as a NACA profile in cross section, wherein a maximum profile curvature f, a curvature skew xf, a profile thickness d, a thickness skew xd, an angle of attack α and an extent Lax,N of each of the outlet guide struts (6) are adapted at predefined spacings along the radial direction from the inner radius ri to the outer radius ra to a predefined operating point or operating region of the axial fan (1) and of the flow which is produced by the impeller at the operating point or operating region, wherein at least the maximum profile curvature f, the curvature skew xf, the profile thickness d, the thickness skew xd, the angle of attack α or the extent Lax,N of an outlet guide strut (6) varies at least in sections in the radial direction along the course thereof, and wherein transitions between the sections of an outlet guide strut (6) are configured in a flowing manner.