Valve Cage Outlet Geometry for Cavitation-Resistant Flow Deflection

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Solution Overview

Problem

Existing valve cages do not effectively manage the flow of process fluid outside the valve cage, leading to turbulence and increased tendencies for cavitation and wear.

Innovation Solution

The valve cage design incorporates arched or convex external contour sections and strategically arranged exit openings, utilizing the Coanda effect to guide process fluid flow around the valve cage, preventing turbulence and optimizing flow deflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional valve cage design with straight outlet openings is used, then the structure is simple, but the flow outside the valve cage becomes turbulent causing cavitation and wear

Engineering Contradiction:
Improveresistance to cavitation and wearVSAvoidvalve cage structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The valve cage incorporates arcuate outer contour sections with convex curvature instead of straight surfaces. The outlet openings are positioned in steps between these curved sections, allowing the process fluid to follow the curved path and attach to the outer contour via the Coanda effect. This curvature design guides the flow smoothly around the valve cage, preventing turbulence, cavitation, and wear while maintaining structural integrity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Productivity

If outlet openings are positioned directly on the outer contour, then the flow path is short, but the flow separates and creates turbulence

Engineering Contradiction:
Improveflow efficiencyVSAvoidflow turbulence
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The step structure acts as an intermediary element between the outlet openings and the arcuate outer contour sections. The outlet openings are positioned in these steps, which serve as transition zones that guide the process fluid from the direct outlet path onto the curved outer contour. This intermediate step structure enables the flow to attach to the curved surface and follow it smoothly, preventing direct separation and turbulence while maintaining efficient flow path.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enhances the flow of process fluid outside the valve cage, reducing turbulence and the likelihood of cavitation and wear, thereby improving the operational efficiency and longevity of the valve.

Implementation Method 1

utilizing the Coanda effect to guide process fluid flow around the valve cage

Methodology Applied
Scientific EffectCoanda effect: Coanda Effect

Data Source

PatentEP4352391B1Valve cage for a control valve
Publication Date: 2025.04.02 SAMSON AG
  • EP4352391B1 patent drawingFigure 1
  • EP4352391B1 patent drawingFigure 2
  • EP4352391B1 patent drawingFigure 3~4

AI summary

The invention relates to a valve cage (100) for a control valve (10), comprising a plurality of throttle channels (104) which extend from an inner contour of the valve cage (100) to its outer contour and penetrate the valve cage (100), each throttle channel (104) having an inlet opening (106) on the inner contour side and an outlet opening (110) on the outer contour side when viewed in the flow direction (S). The invention is characterised in that, when viewed in the circumferential direction (u), the valve cage (100) has a plurality of arcuate outer contour portions (112) which are each separated from one another via a step (114) acting as a tear-off edge, and in that the throttle channels (104) are arranged so that they extend in such a way that the outlet openings (110) of the throttle channels (104) on the outer contour side are arranged in the step (114) between two outer contour portions (112).