Centrifugal Compressor Hub Lightening Hole Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Centrifugal compressors face challenges in evenly distributing stress across the hub when the impeller rotates, leading to uneven stress distribution and high moment of inertia.
Innovation Solution
The centrifugal compressor design includes a hub with a lightening hole on its external radial surface between the positive and negative pressure surfaces of the blades, with the hole being closer to the positive pressure surface, reducing the thickness of the hub portion experiencing low stress and maintaining thickness where high stress occurs, thereby reducing moment of inertia and stress unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a through hole is formed in the hub to reduce moment of inertia, then the impeller's moment of inertia is reduced, but the stress distribution in the hub becomes uneven
Solution Approach 1:
The patent applies local quality by making the hub thickness non-uniform: the hub is thinner in the region corresponding to the positive pressure surface (lower stress area) and thicker in the region corresponding to the negative pressure surface (higher stress area). This localized variation in thickness optimizes both weight reduction and stress distribution, with the lightening hole positioned closer to the positive pressure surface to remove material where it is least needed structurally.
Solution Approach 2:
The patent employs asymmetry by positioning the lightening hole offset toward the positive pressure surface rather than at the center, and by creating asymmetric hub thickness distribution. The hub thickness varies circumferentially, being thinner near the positive pressure surface and thicker near the negative pressure surface, which balances the stress distribution while maintaining moment of inertia reduction.
2Speed
If the hub thickness is reduced to lower moment of inertia, then the impeller rotates more efficiently, but the structural strength and stress resistance decrease
Solution Approach 1:
The hub is designed with locally varied thickness to optimize the strength-to-weight ratio. The thinner region is positioned where stress is lower (positive pressure surface side), while the thicker region is positioned where stress is higher (negative pressure surface side). This local quality variation maintains structural strength in critical areas while reducing overall moment of inertia for improved rotation efficiency.
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 reduces the impeller's moment of inertia and minimizes stress unevenness, leading to a more balanced distribution of forces and reduced thrust load during rotation.
Implementation Method 1
The lightening hole reduces the moment of inertia of the impeller
Implementation Method 2
a plurality of blades provided on the external radial surface of the hub, the plurality of blades each having a positive pressure surface and a negative pressure surface extending from one side of the external radial surface toward the other side of the external radial surface, and being of a positive pressure and a negative pressure, respectively, when the impeller rotates
Data Source
AI summary
A centrifugal compressor comprises an impeller including a hub and a plurality of blades. Each blade has a positive pressure surface and a negative pressure surface extending from one side of an external radial surface toward the other side of the external radial surface and being of a positive pressure and a negative pressure, respectively, when the impeller rotates. The hub has a lightening hole that opens to the external radial surface between the positive pressure surface and the negative pressure surface of the plurality of blades. The lightening hole is provided closer to the positive pressure surface of the blade than the negative pressure surface of the blade.