Breathing Apparatus Blower Diffuser for Pressure and Noise Control
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Solution Overview
Problem
Blowers for breathing apparatuses face challenges in achieving improved static pressure, reducing noise, and managing pressure instabilities and reverse flow effectively.
Innovation Solution
The blower design incorporates a diffuser with cascading aerofoil elements, both planar and circumferential, arranged spirally and offset to direct airflow efficiently, reducing noise and stabilizing reverse flow by aligning it with forward flow, thereby enhancing static pressure and reducing blade pass noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a conventional diffuser design is used, then the structure is simple, but static pressure is insufficient and reverse flow cannot be managed effectively
Solution Approach 1:
The diffuser is segmented into multiple cascades, each cascade containing multiple rows of diffuser elements. This segmentation allows the diffuser to handle reverse flow in a controlled manner while progressively increasing static pressure, resolving the contradiction between simple structure and effective reverse flow management with adequate pressure generation.
Solution Approach 2:
The diffuser elements are designed to dynamically respond to flow direction changes. During reverse flow conditions, the cascading structure allows elements to redirect flow adaptively, enabling the diffuser to maintain effectiveness under varying operational conditions while managing pressure instabilities.
2Stability of the object's composition
If diffuser elements are arranged in a simple pattern, then manufacturing is easier, but pressure instabilities and noise increase
Solution Approach 1:
The diffuser elements within each cascade are arranged asymmetrically with offset positions rather than in simple symmetric patterns. This asymmetric arrangement disrupts coherent pressure instabilities and reduces blade pass noise while maintaining manufacturing feasibility through standardized element repetition across cascades.
Solution Approach 2:
The diffuser elements are arranged in multiple rows across multiple cascades, adding dimensional complexity to the arrangement. This multi-dimensional configuration distributes flow more evenly and stabilizes pressure by preventing localized instabilities, while the modular cascade structure maintains ease of manufacture.
3Object-affected harmful factors
If reverse flow is not managed, then the structure remains simple, but noise increases and operational stability decreases
Solution Approach 1:
The cascading diffuser structure converts harmful reverse flow into beneficial flow redirection. The multiple cascades progressively guide reverse flow through a series of diffuser elements that redirect it toward the outlet, transforming what would be noisy, unstable reverse flow into a controlled flow pattern that reduces noise and improves operational stability.
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 diffuser configuration effectively increases static pressure, mitigates pressure instabilities, and redirects reverse flow to align with forward flow, resulting in reduced noise and improved operational stability of the blower.
Implementation Method 1
diffuser elements redirect reverse flow such that the reverse flow moves in the same direction as forward flow. This helps to reduce blade pass noise caused by pressure instabilities.
Implementation Method 2
The diffuser elements are aerofoils.
Data Source
AI summary
A blower for a breathing apparatus has a diffuser for increasing static pressure and/or reducing noise and/or mitigating pressure instabilities and/or managing reverse flow.