Turbine Rotor Blade Spanwise Spacing Optimization
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Solution Overview
Problem
Turbines used in exhaust turbochargers for automobiles face challenges with increased blade-to-blade distance and flow rate losses due to reduced blade numbers, leading to higher moment of inertia and increased fluid flow rates on the tip side, which results in increased losses.
Innovation Solution
The turbine rotor blade design features a hub surface inclined along the axis with rotor blades arranged such that the blade-to-blade distance in the throat portion is minimized by optimizing the dimensionless span length and blade angle distribution, ensuring the value Lt/r is within 0.2 to 0.65 and l/L is between 0.3 to 0.65, and maintaining a constant blade angle in a specific chordwise range, thereby reducing fluid flow rates and losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the number of blades is reduced to suppress the moment of inertia and improve transient response, then the transient response is improved, but the blade-to-blade distance increases and loss increases
Solution Approach 1:
The patent applies local quality by optimizing the blade-to-blade distance distribution along the blade span. Specifically, the dimensionless blade-to-blade distance Lt/r is set to be maximum at positions where the dimensionless span length is 0.2 to 0.65, creating a non-uniform distribution that concentrates blade spacing optimization in the mid-span region where it most effectively reduces loss while maintaining the reduced blade count for good transient response.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the dimensionless blade-to-blade distance Lt/r and its distribution along the blade span. The parameter Lt/r is optimized to achieve a specific profile where it reaches its maximum value in the mid-span region (dimensionless span length 0.2 to 0.65), which mathematically minimizes the integral of blade-to-blade distance and thereby reduces loss while maintaining fewer blades.
2Strength
If the blade thickness on the hub side is increased to handle high rotational speed, then the structural strength is improved, but the distance between blades decreases and the number of blades cannot be increased
Solution Approach 1:
The patent applies local quality by creating a non-uniform blade-to-blade distance distribution along the blade span. The dimensionless blade-to-blade distance Lt/r is optimized to be maximum at mid-span positions (dimensionless span length 0.2 to 0.65), which compensates for the reduced number of blades and maintains effective flow control in the critical mid-span region where the hub-side thick blades are located.
Solution Approach 2:
The patent transitions from considering only the number of blades (one-dimensional approach) to optimizing the blade-to-blade distance distribution along the blade span (adding the spanwise dimension). By controlling Lt/r as a function of dimensionless span length, the patent creates a two-dimensional optimization space that allows fewer blades to achieve equivalent or superior performance through strategic spacing variation along the blade height.
3Weight of moving object
If the blade-to-blade distance on the tip side of the throat portion increases due to reduced blade number, then the moment of inertia is reduced, but the flow rate on the tip side increases and loss increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform blade-to-blade distance distribution along the blade span. The dimensionless blade-to-blade distance Lt/r is optimized to be maximum at positions where the dimensionless span length is 0.2 to 0.65, which are the mid-span regions. This local optimization ensures that the most critical sections for loss reduction are properly spaced, while allowing greater spacing at the tip end where it contributes more to reducing moment of inertia.
Data Source
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AI summary
A turbine rotor blade according to at least one embodiment to be connected to a rotational shaft so as to be rotatable around an axis includes a hub having a hub surface inclined with respect to the axis in a cross-section along the axis; and a plurality of rotor blades disposed on the hub surface. In a throat portion where a blade-to-blade distance between two adjacent rotor blades is smallest, a value (Lt/r) obtained by dividing the blade-to-blade Lt at a given radial position by a distance r from the axis to the radial position is maximum at a position where a dimensionless span length is in a range of 0.2 to 0.65, assuming that the dimensionless span length is 0 at a position of a root end portion on a hub side and is 1 at a position of a tip end portion opposite to the hub side.