Turbine Rotor Blade Protrusions Mitigate Flow Separation
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Solution Overview
Problem
Turbine rotor blades in aircraft turbojets face performance losses due to harmful detachment of air flow boundary layers, particularly on the extrados surface, leading to vortex disturbances that reduce efficiency.
Innovation Solution
The placement of protrusions along the trailing edge of turbine rotor blades, specifically halfway up and near the radial ends, with a rounded stud shape and wave-like profiles, helps to attenuate these detachment phenomena by modifying the blade profile to reduce yield loss and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the number of turbine blades is decreased to reduce weight, then blade weight is reduced, but aerodynamic performance deteriorates due to increased flow separation and vortex disturbances
Solution Approach 1:
The patent applies local quality by introducing protrusions at specific locations on the blade surface (trailing edge region) rather than modifying the entire blade structure. These localized protrusions create favorable flow conditions precisely where separation occurs, maintaining aerodynamic efficiency without adding overall blade weight or requiring additional blades.
Solution Approach 2:
The patent changes the geometric parameters of the blade surface by adding protrusions with specific dimensions (height 0.5-5mm, length 5-20mm). This modifies the flow field characteristics locally, preventing boundary layer separation and reducing vortex formation, thereby maintaining efficiency with fewer blades.
2Loss of energy
If protrusions are added to the blade surface to prevent flow separation, then aerodynamic performance is improved, but blade complexity increases
Solution Approach 1:
The patent segments the solution by dividing the protrusion configuration into discrete, localized elements distributed along the trailing edge. Rather than a continuous complex structure, separate protrusions are placed at specific intervals, simplifying manufacturing while achieving flow control at critical locations.
Solution Approach 2:
Instead of trying to prevent flow separation through complex blade profile modifications or additional active control systems, the patent uses simple protrusions that create favorable pressure gradients passively. This inverted approach uses geometric simplicity to achieve what complex systems would attempt to accomplish through active means.
3Reliability
If protrusions are placed at the trailing edge to reduce separation zone width, then flow attachment is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs partial action by placing protrusions only in the critical trailing edge region where separation occurs most severely, rather than along the entire blade span. This concentrated approach achieves flow control where needed most while reducing the cumulative tolerance stack-up and simplifying quality control compared to full-span modifications.
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 solution effectively reduces the width of the detachment zone, improving aerodynamic behavior and overall performance by minimizing vortex disturbances and enhancing the structural integrity of the blades.
Implementation Method 1
harmful 'separation' of the entrained air on the upper surface... detachment of air flow boundary layers, particularly on the extrados surface
Data Source
Figure 1~2
Figure 3~4
AI summary
According to the invention, one or more projections (25) are formed on the turbine blade on the suction side (21) thereof in the vicinity of the trailing edge (17) thereof. Such protrusions reduce the separation area in the vicinity of the blade surface, which is responsible for the interference affecting the turbine yield.