Cylindrical Air Guide Reduces Pressure Loss in Turbine Separators
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Solution Overview
Problem
Conventional air/oil separators in gas turbine engines experience undesirable pressure losses due to air friction caused by differences in rotational velocities within free vortices and the use of baffles, which create miniature vortices and irregular radial shapes, leading to inefficiencies in air flow management.
Innovation Solution
A cylindrical air guide is introduced within the rotatable outlet shaft of the air/oil separator, coaxially mounted and rotating with the shaft, which reduces air friction by limiting the difference in rotational velocities and preventing airflow from reaching the central axis, thereby minimizing pressure losses. The air guide is designed with a smaller diameter within a larger shaft, creating an annular flow path and using smooth surfaces to facilitate airflow, and is fabricated to be lightweight and easier to produce than conventional cross-shaped baffles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional baffles are placed down the central axis of the hollow shaft in a radial cross configuration, then the hollow shaft is divided into radial quadrants, but this creates miniature vortexes that cause undesirable pressure loss from vortex air friction
Solution Approach 1:
The patent removes the central cross-shaped baffles from the hollow shaft, extracting the source of miniature vortexes and pressure losses. Instead, a free vortex chamber is positioned at the open end of the hollow shaft, allowing the air-oil mixture to vortex externally without creating internal friction losses within the shaft structure.
Solution Approach 2:
The free vortex chamber acts as an intermediary device that handles the air-oil separation process externally. By positioning the vortex chamber at the shaft end rather than inserting baffles into the shaft, the system mediates the separation function without introducing harmful internal structures that would create friction and pressure losses.
2Ease of operation
If baffles are used to manage air flow in the hollow shaft, then air flow direction can be controlled, but the irregular radial shape creates additional air friction and pressure loss
Solution Approach 1:
The patent employs a curved, free vortex chamber design instead of straight radial baffles. The vortex chamber's curved geometry naturally guides air flow in a smooth rotational pattern, eliminating the sharp edges and irregular radial shapes of cross baffles that would create additional air friction and pressure losses.
3Loss of energy
If a cylindrical air guide is introduced within the rotatable outlet shaft, then air friction is reduced by limiting the difference in rotational velocities, but the device complexity increases
Solution Approach 1:
The cylindrical air guide is nested within the rotatable outlet shaft, with the air guide having a smaller diameter than the shaft's inner circumference. This nested configuration allows the air guide to rotate with the shaft while maintaining a coaxial arrangement that limits rotational velocity differences and reduces air friction, without requiring a completely separate external structure.
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 cylindrical air guide significantly reduces air friction and pressure losses by minimizing the difference in rotational velocities, maintaining a consistent radial cross-sectional area, and using less material, thus enhancing the efficiency of air flow management in gas turbine engines.
Implementation Method 1
The exiting air travels at an axial speed downstream a length of the hollow shaft, while also swirling at a radial, or rotational, flow velocity around an inner circumference of the exit shaft. In the free vortex, the rotational flow velocity of the air is inversely proportional to the distance from the axial center of the hollow shaft
Implementation Method 2
The rotational velocity of the air traveling down the central axis of the hollow shaft is significantly higher in the rotational velocity of the air traveling near the inner circumference of the hollow shaft. This difference in rotational velocities in the free vortex creates air friction
Data Source
AI summary
An air/oil separator for a gas turbine engine includes a drive shaft having a central axis extending in an axial direction, a free vortex chamber mounted radially around the drive shaft, a separation chamber coupled with the free vortex chamber in the axial direction opposite to the drive shaft, and a rotatable outlet shaft radially rotatable and having an inlet end coupled with the separation chamber opposite to the free vortex chamber, an outlet end, and a hollow interior chamber therebetween. The hollow interior chamber has an inner circumference extending in the axial direction a cylindrical air guide extending coaxially therein. The cylindrical air guide has a nonporous cylindrical main body, an upstream end fixedly coupled with the inlet end of the rotatable outlet shaft, and a downstream end coaxially disposed within the outlet end of the rotatable outlet shaft.