Pressure Equalizing Orifice for Gas Turbine Vane Baffles
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Solution Overview
Problem
In gas turbine engines, completely sealed baffles in vane cavities experience a pressure difference between the inside and outside, leading to potential collapse, which is mitigated by thick walls or ribs, but these add weight and complexity. There is a need for a baffle design that reduces this pressure difference.
Innovation Solution
A partial space-eater baffle with a hollow interior and a single opening that connects the baffle interior to the vane cavity, with a baffle opening area between 32x10-5 and 9.7x10-3 square centimeters, and a baffle volume to opening area ratio between 25 and 1270 centimeters, to equalize pressure between the vane cavity and the baffle interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If completely sealed baffles are used in vane cavities, then structural integrity is maintained, but pressure difference causes potential collapse requiring thick walls or ribs which increase weight and complexity
Solution Approach 1:
The invention extracts the sealing function from the baffle structure by introducing a separate seal member that selectively seals the baffle opening only during idle conditions. This allows the baffle opening to remain open during operation for pressure equalization, eliminating the need for thick walls or ribs while maintaining structural integrity when needed.
Solution Approach 2:
The seal member dynamically changes its sealing state based on engine operating conditions. During idle conditions, the seal member seals the opening to maintain structural integrity. During operation, the seal member opens to allow pressure equalization, preventing collapse without requiring thick walls or complex rib structures.
2Stress or pressure
If thick baffle walls or numerous ribs are added to prevent collapse, then pressure difference resistance is improved, but weight and design complexity increase
Solution Approach 1:
The invention extracts the pressure resistance function from the baffle structure itself and transfers it to the dynamic sealing mechanism. The seal member provides pressure resistance only when needed (during idle conditions), while allowing pressure equalization during operation, thereby eliminating the need for heavy thick walls or ribs.
Solution Approach 2:
The invention changes the operational parameters of the baffle opening by controlling its sealing state dynamically. The opening area transitions from sealed (during idle) to open (during operation), allowing the thin-walled baffle to resist pressure differences only when structurally needed, rather than requiring constant thick walls for all conditions.
3Stress or pressure
If the baffle opening area is increased for pressure equalization, then pressure difference is reduced, but structural support and sealing complexity increase
Solution Approach 1:
The invention segments the sealing function from the baffle structure by using a separate, movable seal member. This allows the baffle opening to be effectively large (for pressure equalization) while the seal member provides selective sealing capability, avoiding the need for complex integrated sealing structures or multiple support elements.
Solution Approach 2:
The seal member acts as an intermediary element between the baffle opening and the external environment. It mediates the conflicting requirements by providing sealing when needed and allowing opening when needed, simplifying the overall design compared to creating a complex integrated structure that must simultaneously provide both functions.
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
The design effectively reduces the pressure difference across the baffle, preventing collapse while minimizing weight and complexity by allowing controlled airflow to equalize pressures, thus enhancing structural integrity and efficiency.
Implementation Method 1
a baffle opening area fluidly connects the vane cavity to the baffle interior... effectively reduces the pressure difference across the baffle... allowing controlled airflow to equalize pressures
Data Source
Figure 1
Figure 2
Figure 3A~3D
AI summary
Module for a gas turbine engine including: a disk (108) rotatable about an engine central axis (A) and a vane (106) fixedly disposed upstream of the disk (108), the vane (106) being hollow and including a vane cavity (122) having a vane longitudinal span between a vane upstream opening and vane downstream opening, the vane (106) including: a baffle (130) fixedly supported within the vane cavity (122), the baffle (130) having a hollow interior (129) and a longitudinal span between a baffle upstream surface and a baffle downstream surface, the baffle longitudinal span being less than the vane longitudinal span; wherein a baffle opening area fluidly connects the vane cavity (122) to the baffle interior (129), the baffle opening area is between 32 x 10-5 square centimetres (5.0 x 10^-5 square inches) and 9.7 x 10-3 square centimetres (1.5 x 10^-3 square inches).