Ringed Propeller Fan Blade Curvature to Suppress Trailing Vortices
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Solution Overview
Problem
Ring-equipped propeller fans suffer from dead water areas on the suction surfaces where airflow stagnates, leading to increased trailing vortices and energy loss, which deteriorates air-sending performance.
Innovation Solution
The propeller fan design includes blades with a curved portion projecting towards the pressure surface, with a maximum axial-direction height at the trailing edge, and a ring connection forming a reduced dead water area, suppressing trailing vortex generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the number of blades of the propeller fan is increased to increase the air intake area, then the air intake performance is improved, but the rotational inertia increases and the responsiveness deteriorates
Solution Approach 1:
The propeller fan blade is divided into multiple sections along the radial direction, with each section having a different number of blades. Specifically, the inner radius section has a first number of blades, the middle radius section has a second number of blades, and the outer radius section has a third number of blades. This segmentation allows optimization of both air intake area and rotational inertia by varying blade count in different regions.
Solution Approach 2:
Different sections of the propeller fan blade are designed with locally optimized characteristics. The inner radius section, middle radius section, and outer radius section each have different blade counts tailored to their specific functional requirements, achieving local quality optimization that resolves the contradiction between overall air intake area and rotational inertia.
2Area of moving object
If the number of blades of the propeller fan is increased to increase the air intake area, then the air intake performance is improved, but the torque required for rotation increases
Solution Approach 1:
The propeller fan blade is segmented radially into three sections with different blade counts. This segmentation reduces the overall number of blades compared to a uniform design, thereby reducing the torque required for rotation while maintaining adequate air intake area through optimized local blade distribution.
Solution Approach 2:
Each radial section of the propeller fan blade is designed with locally optimized blade counts. The inner, middle, and outer sections have different blade numbers that are optimized for their specific positions, reducing the total blade count and associated torque requirements while preserving air intake performance where most needed.
3Productivity
If the refrigerant flow rate through the evaporator is increased to improve cooling capacity, then the cooling performance is improved, but the risk of refrigerant liquid hitting the propeller fan increases
Solution Approach 1:
A guide vane is introduced as an intermediary component between the refrigerant flow and the propeller fan. The guide vane redirects the refrigerant flow path, preventing liquid refrigerant from directly contacting the propeller fan while allowing the refrigerant to continue flowing through the evaporator at high rates for improved cooling capacity.
4Reliability
If a guide vane is added to redirect refrigerant flow and prevent liquid from hitting the propeller, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The guide vane is merged with the existing propeller fan structure, forming an integrated assembly. This combining approach provides the necessary refrigerant flow redirection and propeller protection functionality while minimizing the increase in device complexity by utilizing the existing structural framework.
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 design reduces dead water areas and trailing vortices, improving air-sending performance and reducing energy loss, while maintaining airflow rate and efficiency.
Implementation Method 1
a propeller fan that rotates to generate a pushing force on air to be sucked into the air inlet
Data Source
Figure 1
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AI summary
A propeller fan (10) includes a blade (14) that is configured to rotate around a predetermined rotation axis (A) and a ring (16) that is connected to a blade end (20) of the blade (14). The blade (14) includes a curved portion (32) on the blade end (20) side, the curved portion (32) having, in a rotational radial direction of the blade (14), a cross-sectional shape projecting toward a pressure surface side in a convex manner. In the curved portion (32), when a height from the position of a blade root (18) on a camber line (36) in a direction along the rotation axis (A) is an axial-direction height (H) and the position at which the axial-direction height (H) becomes maximum in the rotational radial direction is a maximum curve position (X2), the axial-direction height (H) at the maximum curve position (X2) is maximum on a trailing edge (24) side of the blade (14) .