Ducted Fan Impeller Camber Profile for Low-Flow Stall Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing impellers for ducted fans face efficiency challenges in high-pressure or low-flow situations, with reaction blades stalling and impulse blades being inefficient in lower pressure or higher flow scenarios, especially at increased rotational speeds.
Innovation Solution
The impeller design features blades with a camber that flattens from the root to the tip, transitioning from impulse-driven flow towards the hub to pressure-driven flow towards the tip, with varying camber, impulse ratio, and stagger angle across the blade span, combining impulse and pressure-driven functionalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reaction blades are used to generate airflow through pressure change, then efficiency is improved in normal flow situations, but efficiency deteriorates in high pressure or low flow situations where blades may stall
Solution Approach 1:
The blade design implements different camber characteristics at different locations along the blade span. The root portion has higher camber (50-60 degrees) optimized for pressure-driven flow, while the tip portion has lower camber (25-35 degrees) optimized for impulse-driven flow. This local differentiation allows each section to operate optimally under different flow conditions, preventing stall in high pressure situations while maintaining efficiency in lower pressure situations.
2Productivity
If impulse blades are used to impart momentum to airflow, then efficiency is improved in high pressure or low flow situations, but efficiency deteriorates in lower pressure or higher flow situations
Solution Approach 1:
The blade is segmented into functionally distinct regions along its span. The root region (higher camber) handles pressure-driven flow for lower pressure situations, while the tip region (lower camber) handles impulse-driven flow for high pressure situations. This segmentation allows the single blade design to adapt to varying operating conditions, maintaining efficiency across a wide operational range from low to high pressure and flow rates.
3Ease of manufacture
If uniform camber is used across the blade span, then manufacturing is simplified, but performance deteriorates due to inability to optimize for varying flow conditions across the blade
Solution Approach 1:
The blade employs non-uniform camber distribution along its span, with the root portion having higher camber (50-60 degrees) and the tip portion having lower camber (25-35 degrees). This local quality variation optimizes performance across different flow conditions - the higher camber at the root captures pressure-driven flow effectively, while the lower camber at the tip maintains efficiency in impulse-driven flow conditions, thereby improving overall productivity despite increased manufacturing complexity.
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
This design enhances efficiency across a wider operating range, particularly at lower volumetric flow rates, offering improved performance compared to traditional impulse and axial fans by blending impulse and reaction functionalities.
Implementation Method 1
An impulse blade is designed to impart momentum to the airflow by the surfaces and the blades may be flat or non-aerofoil shaped to directly impart motion to the airflow
Implementation Method 2
A reaction blade is designed to generate air flow as a result of pressure change, and the blades may be aerofoil shaped to create the pressure differential across the blade
Data Source
AI summary
An impeller (20, 120) for a ducted fan arrangement (10, 110), the impeller (20, 120) including a hub (24, 124) and a plurality of blades (26, 126) extending radially from the hub (24, 124), each of the plurality of blades (26, 126) including a root (28, 128) proximate the hub (24, 124) and a tip (30, 130). A camber of each of the plurality of blades (26, 126) is arranged to flatten or reduce between the root (28, 128) and the tip (30, 130). A fan arrangement (10, 110) including such an impeller (20, 120) is also disclosed.