Turbocharger Impeller Asymmetric Flow Path Width Noise Reduction
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Solution Overview
Problem
In turbochargers, minimizing the gap between the scroll portion's tongue and the turbine blade to improve efficiency can lead to noise due to pressure fluctuations, especially at low flow speed areas downstream of the tongue portion.
Innovation Solution
The turbocharger design includes an impeller with turbine blades arranged at unequal intervals and inter-blade flow path widths, which disperses pressure fluctuations across multiple frequency ranges, reducing noise without widening the gaps between the blades and tongue portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gap between the tongue portion and the turbine blade is made small to improve efficiency, then the efficiency of the turbocharger is improved, but noise occurs due to pressure fluctuations when the turbine blade passes through the low flow speed area
Solution Approach 1:
The patent applies asymmetry by making the flow path widths of the inter-blade flow path portions unequal. Specifically, at least one inter-blade flow path portion has a different flow path width in the circumferential direction compared to others. This asymmetric configuration disrupts the periodic pressure fluctuations that occur when turbine blades pass through the low flow speed area, thereby reducing noise generation while maintaining the small gap between the tongue portion and turbine blade for efficiency.
Solution Approach 2:
The patent applies local quality by varying the flow path width at specific locations between the turbine blades. Instead of uniformly adjusting all inter-blade flow path portions, only certain portions are modified to have different flow path widths. This localized adjustment targets the specific issue of pressure fluctuations and noise generation in the low flow speed area without affecting the overall efficiency gained from the small tongue-blade gap.
2Object-generated harmful factors
If the gap between the tongue portion and the turbine blade is widened to suppress noise, then noise due to pressure fluctuations is reduced, but the efficiency of the turbocharger deteriorates
Solution Approach 1:
The asymmetric flow path width configuration allows noise suppression through flow distribution adjustment rather than gap widening. By creating unequal flow paths, the pressure fluctuations are dispersed and reduced without requiring an increase in the tongue-blade gap, thus avoiding efficiency deterioration.
Solution Approach 2:
The patent changes the flow path width parameter of the inter-blade flow path portions to control pressure fluctuations. By adjusting this parameter asymmetrically, the system achieves noise reduction through flow dynamics modification rather than geometric gap adjustment, preserving the efficiency benefits of the small tongue-blade gap.
3Ease of manufacture
If the flow path width of inter-blade flow path portions is made uniform, then the structure is simple and easy to manufacture, but pressure fluctuations occur causing noise
Solution Approach 1:
The patent introduces asymmetry in the flow path widths of inter-blade flow path portions to suppress noise caused by pressure fluctuations. This design deviates from the uniform configuration, requiring additional manufacturing considerations, but effectively reduces noise by disrupting the periodic pressure variations that occur with uniform flow paths.
Solution Approach 2:
The patent implements local quality variations in the flow path widths at specific inter-blade portions. This selective modification targets the noise generation mechanism while maintaining relative manufacturing simplicity by only adjusting specific flow path dimensions rather than redesigning the entire turbine structure.
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 effectively suppresses noise by dispersing pressure fluctuations across multiple frequency ranges, maintaining efficiency without increasing the gaps between the turbine blades and tongue portions.
Implementation Method 1
noise may occur due to pressure fluctuations when the turbine blade passes through a low flow speed area of the exhaust gas occurring on the downstream side of the tongue portion
Data Source
AI summary
This turbocharger includes: an impeller which includes a hub provided to be rotatable around a center axis and a plurality of turbine blades arranged on the outside of the hub in a radial direction at intervals in a circumferential direction around the center axis; and a turbine housing which is disposed on the outside of the impeller in the radial direction and forms a scroll flow path guiding an exhaust gas toward the impeller on the inside of the radial direction while turning the exhaust gas in the circumferential direction, wherein a flow path width in the circumferential direction of at least one of a plurality of inter-blade flow path portions formed between the plurality of turbine blades is different from a flow path width of the another of the plurality of inter-blade flow path portions.