Spray Head Bluff Body Noise Reduction
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Solution Overview
Problem
Existing spray devices experience noise excitation due to blown air, which is acoustically harmful to the environment and operators.
Innovation Solution
The integration of bluff bodies at the upstream edges of discharge and slide openings in the spray head design, which are molded as part of a one-piece plastic component, reduces noise emission by directing the blown air effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If blown air is used to deliver the spray medium, then the spray medium can be effectively discharged into the air stream, but noise excitation occurs at the discharge opening which is acoustically harmful
Solution Approach 1:
A bluff body is introduced as an intermediary element between the blown air flow and the discharge opening. This bluff body mediates the interaction by creating a shaded region that prevents direct impingement of the air jet on the opening edge, thereby reducing noise generation while maintaining the transport function of the spray medium.
Solution Approach 2:
The bluff body converts the potentially harmful direct jet impingement on the discharge opening into a beneficial shaded flow pattern. The region behind the bluff body becomes a low-pressure zone that actually enhances spray medium pickup while the bluff body itself acts as a noise shield, transforming the harsh direct flow into a quieter, more controlled flow pattern.
2Ease of manufacture
If the spray head is designed as a one-piece component with feed tube and internal fittings, then manufacturing is simplified, but noise excitation from slide openings may occur
Solution Approach 1:
The spray head is segmented into multiple functional zones with discrete bluff bodies positioned at each opening (discharge opening and slide openings). This segmentation allows each opening to be independently treated with noise-reducing features while maintaining the overall one-piece manufacturing advantage, as the bluff bodies are integrated into the single component.
Solution Approach 2:
Different regions of the spray head are given different local characteristics by positioning bluff bodies specifically at openings subject to direct air flow impingement. The bluff bodies create localized shaded regions at critical openings while leaving other areas of the spray head with different flow characteristics, optimizing both noise reduction and manufacturing 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
Significantly reduces noise emission during operation of the spray head, ensuring a quieter operation without compromising the structural integrity or manufacturing complexity.
Implementation Method 1
By arranging a bluff body at the upstream edge of the discharge opening on the inflow side of the blown air, noises excited at the discharge opening are suppressed
Implementation Method 2
By arranging a bluff body at the upstream edge of the discharge opening on the inflow side of the blown air, noises excited at the discharge opening are suppressed, as a result of which the noise emission of the spray head is significantly reduced
Data Source
Figure 1~3
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Figure 6~7
AI summary
The head has an inlet opening provided for entry of blowing air (40). The supply tube has an outer supply connector for a medium i.e. fluid, and an outlet opening (29) for mixing the medium in the blowing air. A level of the outlet opening lies longitudinal to a flow direction (18) of the blowing air. An interference body (42) is arranged for the blowing air at a blowing side on an upstream lying edge of the outlet opening. The body is designed as a rod i.e. round rod, which is designed as a semi cylinder tube.