Gas Turbine Rotor Blade Tip Vortex Control
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Solution Overview
Problem
Gas turbine engine efficiency is reduced due to flow disturbances caused by leakage airflows through the tip clearance gap, with existing solutions either failing to adequately address the issue or increasing rotor mass, which limits operational speeds and temperatures.
Innovation Solution
The rotor blade design features a unique airfoil configuration with varying stagger and chord angles, particularly in the tip region, which alters the local pressure distribution to minimize leakage mixing losses without altering the leakage flow amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the clearance gap is decreased by reducing tolerances, then leakage airflow is reduced, but manufacturing precision requirements increase and thermal/centrifugal expansion interference occurs
Solution Approach 1:
The patent applies local quality by modifying only the tip region of the airfoil with a specific geometry (rounded or flattened tip, or tip extension) while keeping the rest of the airfoil design unchanged. This localized modification alters the pressure distribution specifically at the tip to reduce leakage flow effects without requiring tight tolerances across the entire blade assembly.
Solution Approach 2:
The patent changes geometric parameters of the airfoil tip region, such as tip radius, tip chord length, or tip shape configuration. These parameter changes modify the local pressure distribution and flow characteristics to reduce leakage mixing losses without affecting the overall clearance gap dimensions or requiring reduced tolerances.
2Loss of energy
If a shroud is attached to the tips of the rotor blades, then vortex induced losses are reduced, but rotor mass increases significantly
Solution Approach 1:
The patent extracts the tip leakage control function from the separate shroud component and integrates it directly into the airfoil tip geometry itself. By incorporating leakage-reducing features (such as rounded tips, flattened tips, or tip extensions) as part of the basic airfoil structure, the solution eliminates the need for additional shroud components while maintaining the benefit of reduced vortex induced losses.
Solution Approach 2:
The patent merges the tip leakage control function with the airfoil structure by integrating tip modification features directly into the airfoil design. This consolidation combines the structural airfoil function with the flow control function in a single integrated component, eliminating the need for separate shroud attachments and reducing overall rotor mass.
3Loss of energy
If the airfoil tip geometry is modified to alter pressure distribution, then leakage mixing losses are reduced, but airfoil design complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the tip region of the airfoil with specific geometric features (rounded tip, flattened tip, or tip extension) while keeping the rest of the airfoil design simple and conventional. This localized approach reduces leakage mixing losses through targeted pressure distribution modification without requiring complex changes to the overall airfoil geometry or design methodology.
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 significantly reduces mixing losses, leading to higher efficiency in gas turbine engines by optimizing airflow characteristics in the tip region.
Implementation Method 1
alters the local pressure distribution to minimize leakage mixing losses
Implementation Method 2
a stagnation point is formed near the leading edge of the airfoil. A stagnation point may be defined as a point in a flow field where velocity of the airflow is approximately zero. At the stagnation point, the airflow separates into a pressure side airflow and a suction side airflow.
Implementation Method 3
This leakage airflow mixes with the suction side airflow forming a vortex.
Data Source
Figure 1~3
Figure 2~4
Figure 5A~7
AI summary
A rotor blade (32) for a gas turbine engine includes an attachment (34) and an airfoil (36). The airfoil (36)has a stagger angle (Φ), a base region (50), a transition region (52) and a tip regions (54). The stagger angle (Φ) changes as the airfoil (36) extends between the attachment (34) and a tip (46). The base region (50) is disposed adjacent to the attachment (34). The transition region (52) is located between the base (50) and the tip (54) regions. A rate of the change of the stagger angle (Φ) in the transition region (52) is greater than a rate of the change of the stagger angle (Φ) in the base region (50). The rate of the change of the stagger angle (Φ) in the transition region (52) is greater than a rate of change of the stagger angle in the tip region (54).