Volute Casing Stiffening Elements for Hydraulic Machine Stress Reduction
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Solution Overview
Problem
Hydraulic machines with spiral housings face issues of stress concentration and deformation under high water pressure, leading to efficiency loss and potential damage at the transition points between adjacent segments and the truss ring deck, which existing reinforcement methods have not adequately addressed.
Innovation Solution
The introduction of inwardly bent and welded 'retracted corner' stiffening elements on the inside surface of the volute casing segments, which are designed to distribute stress without significantly affecting the flow, and using segments made from circular arcs of different diameters to reduce stress peaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If reinforcement plates are provided on the outside of segments at transition points, then stress concentration is reduced, but the complexity of manufacturing and additional material usage increase
Solution Approach 1:
Instead of placing reinforcement plates on the outside of the segments as proposed in prior art, the invention inverts the approach by creating stiffening elements from the inner side of the volute casing. The corners of the volute casing are bent inward to form roof-like projections that extend into the interior space, thereby reinforcing the transition points from the inside rather than adding external plates.
Solution Approach 2:
The invention utilizes the flexibility of the volute casing shell itself by bending its corners inward to form stiffening elements. This approach transforms the shell structure to provide self-reinforcement at critical stress points without requiring separate reinforcement components, thereby reducing manufacturing complexity while maintaining strength.
2Strength
If thick materials are used for volute casing segments, then strength and stress resistance are improved, but weight and manufacturing costs increase
Solution Approach 1:
The invention applies local quality by creating stiffening elements only at the specific locations where stress concentration occurs - namely at the transition points between adjacent segments and the traverse ring deck. The corners of the volute casing are bent inward at these critical points to form roof-like projections, while the rest of the volute casing maintains its original thin-walled structure. This localized reinforcement provides necessary strength without increasing the weight of the entire volute casing.
3Strength
If stiffening elements protrude significantly into the volute interior, then stress peaks are reduced, but hydraulic flow is significantly affected
Solution Approach 1:
The invention applies partial action by creating stiffening elements with controlled dimensions that provide sufficient reinforcement without excessive protrusion. The roof-like projections extend inward from the corners of the volute casing by a limited amount - enough to effectively reduce stress peaks at transition points, but not so much as to significantly obstruct the hydraulic flow through the volute casing.
Data Source
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AI summary
The invention relates to a hydraulic machine having an impeller wheel that comprises a plurality of impeller blades; having a spiral housing that encloses the impeller wheel and that is open toward said impeller wheel by a circumferential slit formed by two circumferential edges; having a traverse ring, comprising two traverse ring decks that are connected to one another by tension anchors; wherein the spiral housing is composed of segments that meet in the flow direction and that are welded to each other, the ends of which segments stand on the respective traverse ring deck and are welded to said deck; wherein at the meeting point between two segments that are adjacent to one another and one traverse ring deck a stiffening element is provided that protrudes into the inner space of the spiral housing; and wherein the extension of the stiffening element into the inner space of the spiral housing is so small that the flow is not affected in a significant manner.