Bifurcated Centrifugal Impeller for Tip Clearance Loss Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of increasing pressure ratios in centrifugal compressors is limited by compressor blade tip clearances relative to blade height, particularly in smaller gas turbine engines, leading to stability and performance issues.
Innovation Solution
The implementation of bifurcated impeller blades with blocked zones and optional filler material in centrifugal compressors to restrict flow channels and increase pressure ratios while reducing tip losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pressure ratio of gas turbines is increased, then overall cycle efficiency is improved, but the exit flow area must be decreased which leads to tip clearance becoming a high percentage of blade height, causing compressor stability and performance issues
Solution Approach 1:
The impeller exit is segmented into multiple independent flow channels separated by radial walls extending from the hub to the shroud. This segmentation allows each channel to be independently optimized for flow management while maintaining overall pressure ratio, resolving the contradiction between efficiency improvement and stability maintenance
Solution Approach 2:
The patent introduces a radial dimension for flow channel separation by extending walls from the hub outward to the shroud, creating a three-dimensional flow management structure. This adds a new spatial dimension for controlling flow paths without reducing the overall exit flow area, allowing pressure ratio increase while maintaining compressor stability
2Stress or pressure
If the channel height is reduced to achieve area reductions for higher pressure ratios, then pressure ratio is improved, but the tip clearance becomes a high percentage of blade height, causing surge margin and performance retention issues
Solution Approach 1:
Different regions of the impeller exit are given different qualities through the segmented flow channels. Each channel can have optimized local geometry for its specific flow requirements, allowing high pressure ratio in some regions while maintaining adequate surge margin in others through localized flow control
Solution Approach 2:
The radial walls are positioned upstream in the flow path to pre-organize the flow into distinct channels before the flow reaches the critical exit region. This preliminary flow organization prevents flow instability and surge by establishing controlled flow paths early in the compression process
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 configuration allows for higher pressure ratios and improved efficiency in smaller gas turbines by minimizing tip clearance and enhancing flow management.
Implementation Method 1
centrifugal compressors (impellers)
Implementation Method 2
Increasing the pressure ratio of gas turbines is an effective means of improving overall cycle efficiency
Data Source
AI summary
An impeller for a gas turbine engine includes an impeller hub having an impeller leading edge and an impeller trailing edge and a plurality of bifurcated impeller blades arranged on the impeller hub and extending from the impeller leading edge to the impeller trailing edge, each bifurcated impeller blade having a bifurcated pressure side and a bifurcated suction side. The bifurcated pressure side and the bifurcated suction side of each bifurcated impeller blade separate at a bifurcation point and extend to the impeller trailing edge with a reduced flow channel defined between adjacent bifurcated impeller blades. A blocked zone is defined within each bifurcated impeller blade between the bifurcated pressure side and the bifurcated suction side and each of the bifurcated pressure side and the bifurcated suction side extend tangentially from the bifurcation point at different radii of curvature.