Blower Tube Outlet Projections for High-Speed Airflow Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Backpack type power blowers generate noise due to the ejection of high-speed airflow from the blower tube, which is a nuisance and requires a technology to reduce noise levels effectively.
Innovation Solution
A blower tube with a distal end portion featuring a plurality of radially inward projections, preferably in an odd number, that mingle and change the frequency bands of the noise, thereby reducing noise levels. The projections are designed to alter the airflow direction and frequency, enhancing noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional smooth blower tube is used, then the high-speed airflow is ejected efficiently, but noise levels are high due to the ejection of high-speed airflow
Solution Approach 1:
The blower tube is designed with projections only at the distal end portion, while the rest of the tube maintains a smooth interior surface. This local modification creates turbulence specifically at the ejection point to reduce noise, while preserving laminar flow characteristics in the main body for efficient airflow transport
Solution Approach 2:
The projections at the distal end create controlled turbulence and vibration in the high-speed airflow as it passes through them. This mechanical disturbance breaks up the coherent high-speed jet structure, converting organized kinetic energy into chaotic turbulent motion that reduces noise radiation
2Object-generated harmful factors
If projections are added at distal end portion, then noise frequency bands are complicated and noise is reduced, but device complexity increases
Solution Approach 1:
The blower tube is segmented into two distinct zones: a smooth interior surface zone for the majority of the tube length that maintains flow efficiency, and a modified distal end zone with projections that reduces noise. This segmentation allows each zone to perform its specific function optimally
Solution Approach 2:
The projections modify local geometric parameters at the distal end, changing the flow characteristics from laminar to turbulent in that specific region. This parameter change (from smooth to projected surface) creates frequency complications in the noise spectrum, reducing overall noise levels
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 blower tube effectively reduces noise levels by altering the frequency bands of the noise caused by high-speed airflow ejection, as demonstrated by experimental results showing significant noise reduction in audible frequency bands.
Implementation Method 1
The projections provided at the distal end portion of the blower tube mingle the high-speed airflow to be released from the blower tube. Thereby, the projections can change the frequency bands of noises to more complicated frequency bands and thereby can reduce the noises.
Data Source
AI summary
A blower tube (4) to be connected to a power blower has a tube main body (42) having a distal end portion (42a) diminished in diameter toward its distal end and an attachment (44) to be coupled to the distal end (42a) of the tube main body (42) and including a distal end portion (44a) gradually diminished in diameter toward its distal end. Both these distal end portions (42a, 44a) are each provided three projections at distant position to protrude radially inward toward an axial line of the blower tube (4). The first projections (46) on the tube main body (42) and the second projections (48) on the attachment are positioned offset in phase to align in an alternate order. The blower tube (4) having the projections (46, 48) at the distal end portion can reduce the noise caused by ejection of a high-speed airflow.