Variable Geometry Shrouded Compressor Rotor Design
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Solution Overview
Problem
Turbomachinery faces challenges in independently controlling fluid flow rate and pressure ratio or head, as existing methods often require adjustments that consume power and involve complex geometries or components like bleed ports and variable geometry diffusers.
Innovation Solution
A shrouded impeller design with a rotating and axially translating shroud that adjusts the flow area by receiving or releasing impeller blades, allowing independent control of flow rate and pressure ratio without changing rotational speed or using additional control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a variable geometry diffuser or casing bypass is used to control flow rate, then the flow rate can be adjusted, but the pressure ratio or head changes and additional power is consumed
Solution Approach 1:
The shroud is made dynamically adjustable in the axial direction, allowing it to move relative to the impeller to change the flow area. This dynamic geometry adjustment enables flow rate control without changing rotational speed or using power-consuming bypass mechanisms, directly resolving the contradiction between productivity and energy consumption
Solution Approach 2:
The invention changes the geometric parameter of the shroud's axial position to control flow rate. By varying the axial distance between the shroud and impeller, the flow area is adjusted, enabling independent flow rate control while maintaining constant pressure ratio and avoiding additional power consumption
2Productivity
If machine rotational velocity or inlet guide vanes are adjusted to control flow rate, then flow rate changes, but pressure ratio or head also changes
Solution Approach 1:
The control functions are segmented and separated: the shroud's axial position controls flow rate independently, while the impeller's rotational speed controls pressure ratio independently. This segmentation of control functions allows independent adjustment of flow rate and pressure ratio without the coupled effects present in conventional designs
Solution Approach 2:
The movable shroud provides a dynamic control mechanism that decouples flow rate control from pressure ratio control. By adjusting only the shroud's axial position, flow rate can be varied while the impeller maintains constant rotational speed and constant pressure ratio, achieving independent control
3Productivity
If a shroud is added to create a shrouded impeller, then flow rate control is improved, but device complexity increases
Solution Approach 1:
The shroud serves multiple functions: it contains the fluid flow, provides a surface for axial movement to control flow area, and works with the impeller to create the variable geometry effect. This multi-functionality justifies the added component by providing flow control capability without requiring multiple separate mechanisms
Solution Approach 2:
The shroud is designed with axial mobility relative to the impeller, creating a dynamic configuration that enables flow rate control. This single dynamic degree of freedom (axial movement) provides effective flow control without the complex multi-axis adjustments or multiple moving parts that would increase device complexity further
Data Source
AI summary
A shrouded impeller includes an impeller having a plurality of blades and configured to rotate about an axis, and a shroud disposed adjacent to the impeller and configured to corotate about the axis with the impeller and translate axially relative to the impeller. A method of varying a geometry of a flow area of the shrouded impeller includes rotating the shroud and the impeller about the axis and axially translating the shroud relative to the impeller to increase or decrease a rate of flow between the shroud and the impeller.