Variable Geometry Turbine Nozzle Vane Projections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable geometry radial turbines face efficiency degradation due to fluid leakage and wake generation when nozzle vanes are closed, as the thickness of trailing edges relative to throat width is high, leading to increased fluid widening rates and performance degradation.
Innovation Solution
The implementation of projections on opposing surfaces that cover the gaps between nozzle vanes and opposing surfaces when closed, reducing throat height and fluid leakage, and the use of tapered surfaces to minimize flow direction changes and separation losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gaps are provided between nozzle vanes and opposing surfaces to prevent contact when nozzle vanes turn, then nozzle vanes can rotate freely without immobilization, but fluid leakage increases and turbine efficiency decreases
Solution Approach 1:
A seal member is introduced as an intermediary component between the nozzle vane and the opposing surfaces (nozzle mount and nozzle plate). This seal member fills the gap space, preventing fluid leakage while allowing the nozzle vane to rotate freely. The seal member mediates between the conflicting requirements of maintaining a gap for rotation and closing the gap to prevent leakage.
Solution Approach 2:
The seal member is configured as a flexible element that can deform during the rotation of the nozzle vane. This flexibility allows the seal member to maintain contact with both the nozzle vane and the opposing surfaces throughout the rotation range, effectively sealing the gap while accommodating the motion of the nozzle vane.
2Adaptability or versatility
If nozzle vanes are closed to reduce flow rate, then flow control is achieved, but fluid leakage through gaps increases efficiency loss
Solution Approach 1:
The seal member acts as a mediator that prevents fluid leakage through the gaps between the nozzle vane and opposing surfaces during flow rate control operations. By sealing these gaps, the system achieves efficient flow control without the penalty of leakage-induced efficiency loss.
Solution Approach 2:
The seal member changes its physical state or configuration in response to the nozzle vane position. When the nozzle vane is closed, the seal member effectively seals the gap; when the nozzle vane opens, the seal member allows for the necessary clearance. This dynamic parameter change enables both flow control and leakage prevention.
3Strength
If trailing edge thickness is large relative to throat width when nozzle vanes are closed, then structural strength is maintained, but wake generation increases and performance degrades
Solution Approach 1:
The nozzle vane is designed with non-uniform thickness distribution along its length. The trailing edge portion has reduced thickness compared to the root portion, creating local quality variation. This allows the trailing edge to minimize wake generation while the root portion maintains structural strength.
Solution Approach 2:
Instead of reducing the thickness of the entire nozzle vane, only the trailing edge portion is thinned. This partial action approach maintains overall structural strength while locally optimizing the trailing edge to reduce wake generation and improve turbine performance.
Data Source
AI summary
A variable geometry turbine includes a fluid space formed by a nozzle mount and a nozzle plate; and a plurality of nozzle vanes arranged in the fluid space at certain intervals in the circumferential direction so as to partition the fluid space. The nozzle vanes are supported by shafts on the nozzle mount, in such a manner as to be capable of turning. The flow rate of the discharged fluid can be adjusted by opening or closing the cross-sectional area of a flow path formed by the adjacent nozzle vanes. The nozzle plate is provided with plate projections protruding toward the nozzle vanes further than, at least, end surfaces of the nozzle vanes, so as to cover the spaces between leading edges of the nozzle vanes and trailing edges of the nozzle vanes adjacent thereto, when the nozzle vanes are at a closed position.