Thrust Bearing Flow Restriction for ACM Cooling
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Solution Overview
Problem
Thrust bearings in air cycle machines (ACMs) face challenges in efficiently dissipating heat due to limited cooling air flow, which can lead to thermal distortion and reduced service life, as conventional convective heat transfer methods are not effective enough.
Innovation Solution
A bearing assembly with a thrust runner and thrust bearing that includes a first flow passage between the thrust runner and a face of the thrust bearing, and a second flow passage between the thrust bearing and a housing, where a restriction feature redirects a portion of the fluid flow from the second passage into the first passage, enhancing cooling efficiency by increasing the fluid flow through the primary passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air flow is increased through conventional convective heat transfer, then bearing cooling effectiveness is improved, but the available cooling air flow is limited and cannot be sufficiently increased
Solution Approach 1:
The patent introduces a restriction feature as an intermediary element in the second flow passage that acts as a flow splitter. This mediator redirects a portion of the cooling air from the second flow passage into the first flow passage, enabling more effective cooling of the thrust bearing without requiring additional total cooling air flow from the system.
Solution Approach 2:
The patent changes the flow distribution parameters by using the restriction feature to alter how cooling air is divided between the two flow passages. By adjusting the restriction characteristic, the system optimizes the proportion of air directed through the first flow passage to maximize bearing cooling effectiveness while maintaining the limited total air availability.
2Temperature
If cooling effectiveness is improved by increasing fluid flow through the primary passage, then bearing temperature is reduced, but the total cooling air flow rate must be increased
Solution Approach 1:
The patent applies partial action by using the restriction feature to redirect only a portion of the cooling air from the second flow passage into the first flow passage. This partial redirection is sufficient to improve bearing cooling effectiveness without requiring an increase in the total cooling air flow rate through the bearing assembly.
Solution Approach 2:
The restriction feature serves as an intermediary that redistributes the existing cooling air flow. It mediates between the two flow passages, taking air from the second passage and directing it to the first passage, thereby improving cooling effectiveness without external additional air supply.
3Productivity
If a restriction feature is added to redirect flow, then cooling efficiency is enhanced, but device complexity increases
Solution Approach 1:
The restriction feature is designed with specific geometric parameters (cross-sectional area, position, shape) that can be optimized to achieve the desired flow redistribution. By carefully selecting these parameters, the system enhances cooling efficiency while minimizing the added complexity, as the restriction feature can be integrated into existing bearing assembly components.
Solution Approach 2:
The restriction feature is placed locally within the second flow passage at a specific position to achieve flow redirection. This localized modification enhances cooling efficiency without requiring changes to the entire bearing assembly structure, thereby limiting the increase in overall device complexity.
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 configuration improves the cooling effectiveness of the thrust bearing, reducing the need for additional cooling air flow and enhancing the overall efficiency and thermodynamic performance of the ACM by doubling the fluid flow through the primary passage while maintaining a consistent total flow rate.
Implementation Method 1
A restriction feature restricts a flow of fluid through the second flow passage. A portion of the flow of the fluid in the second passage is diverted to flow into the first flow passage.
Implementation Method 2
The bearings are cooled by passing a cooling air flow through a cavity that is adjacent the bearing. The cooling air flow then exits the cavity and is discharged from the ACM into an ambient environment. The cooling air flow is limited in that it can only cool the bearing using convective heat transfer.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A bearing assembly (42A) includes a shaft (90A) and a thrust runner (68A) attached to the shaft (90A). The shaft runner protrudes radially outward from the shaft. A thrust bearing (66A) is positioned axially adjacent to the thrust runner (68A). A first flow passage (86A) is between the thrust runner (68A) and a first face (74A) of the thrust bearing (66A). A second flow passage (88A) is between a second face (76A) of the thrust bearing (66A) and a housing (70A). A restriction feature (98A) restricts a flow of fluid through the second flow passage (88A).