Turbine Rotor Blade Tip Clearance and Suction Design
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Solution Overview
Problem
Existing turbine rotor blade technologies face challenges in maintaining efficiency due to increased mixing of cooling air, which leads to reduced pressure differences and increased thermal loads, particularly at the blade tip, causing turbulence and heat flux issues that can result in blade breakage.
Innovation Solution
The turbine rotor blade design features a varying clearance between the casing and the tip-side end face, with a progressive reduction in downstream direction, and a stepwise radial position of the tip-side end face to minimize the mixing area of cooling air with mainstream gas, reducing turbulence and thermal loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is supplied to the rotor blade, then the blade is cooled, but the cooling air mixes with the mainstream fluid and causes total pressure loss
Solution Approach 1:
The invention extracts and removes the harmful low-speed cooling air from the tip region before it can mix with the mainstream high-speed fluid. By providing a suction means that actively removes this cooling air, the system prevents the mixing that would otherwise cause total pressure loss, while still maintaining the cooling function through controlled discharge of the removed air.
Solution Approach 2:
The suction means acts as an intermediary mechanism between the cooling air supply system and the mainstream flow. It intercepts the cooling air at the tip, separates it from the mainstream, and controls its discharge, thereby mediating the interaction between cooling requirements and pressure loss prevention.
2Loss of energy
If the tip seal is reinforced to prevent cooling air mixing, then total pressure loss is reduced, but the sealing complexity increases
Solution Approach 1:
The invention uses pneumatic principles by employing a suction means (such as a suction blower or fan) to actively manage the cooling air flow. This pneumatic approach replaces complex mechanical seal structures with a more straightforward suction-based system that controls air mixing through pressure differential rather than physical barriers.
3Loss of energy
If the blade tip clearance is reduced to prevent cooling air infiltration, then cooling air mixing is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention transitions from a static clearance-based approach to a dynamic flow control approach. Instead of relying on fixed geometric clearances that require high manufacturing precision, the system uses an active suction means that dynamically manages the cooling air flow, allowing for more tolerant manufacturing specifications while achieving the same or better performance.
4Temperature
If cooling air flow rate is increased to improve cooling, then blade temperature is reduced, but turbulence and thermal load on the blade increase
Solution Approach 1:
The invention extracts the harmful effects of high-speed cooling air by actively removing and separating it from the blade surface and tip region. The suction means prevents the high-speed cooling air from creating turbulence and excessive thermal load on the blade, while still providing adequate cooling through controlled air supply and removal.
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 enhances turbine efficiency by reducing total pressure loss and thermal loads, suppressing performance degradation, and optimizing energy conversion into rotational energy, while also reducing the area of turbulent flow fields.
Implementation Method 1
low-speed air that flows from the pressure surface toward the suction surface through between the tip and the casing
Implementation Method 2
A difference in the blade surface Mach number between the suction surface and the pressure surface produces a difference in pressure between the suction surface and the pressure surface, which will rotate the rotor blade
Implementation Method 3
the turbulence of a flow field on the tip side has a large influence on the blade portion. More specifically, the turbulence of the flow field increases heat flux from the fluid side toward the blade portion
Data Source
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AI summary
A turbine blade is provided that can reduce a total pressure loss at a blade cross-section on a tip side of the turbine rotor blade and suppress degradation in performance even if cooling air mixes in toward the rotor blade. The turbine rotor blade mounted to a rotor to form a turbine blade row rotating in a stationary member includes a platform forming a gas passage through which a mainstream gas flows and an airfoil extending from a gas passage plane in a radial direction vertical to the rotational axis of the rotor, the gas passage plane being a plane of the platform and forming the gas passage. A clearance between the tip-side end face which is a leading end-side end face of the airfoil and the stationary member facing the tip-side end face is defined so as to be smaller on the downstream side in the flow direction of the mainstream gas than on the upstream side.