Air Data Probe Water Dam Assembly Without Tack Brazing
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Solution Overview
Problem
Conventional methods for installing water dams and bulkheads in pitot tubes using low temperature braze alloys result in floating debris and misalignment, posing a risk of foreign object debris and measurement errors.
Innovation Solution
A monolithic water dam is mechanically stabilized on the heater coil during installation, eliminating the need for low temperature tacking braze and preventing misalignment, while allowing for retrofitting into existing probes without redesign.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low temperature braze alloy is used to tack the water dam to the heater, then the water dam can be retained during installation, but the braze reflows and floats to the surface creating foreign object debris
Solution Approach 1:
The patent removes the low temperature braze alloy from the assembly process entirely. Instead of using braze to attach the water dam to the heater, the design allows the water dam to be mechanically retained by the heater coil structure itself, eliminating the source of debris generation
Solution Approach 2:
The heater coil acts as an intermediary mechanical retention structure between the water dam and the final assembly. The coil provides physical support and positioning for the water dam during installation without requiring additional braze materials that could contaminate the system
2Reliability
If conventional tack brazing is used to affix the water dam, then the water dam is secured to the heater, but misalignment occurs during installation
Solution Approach 1:
The heater coil is pre-formed with a specific geometry that provides mechanical retention features for the water dam before final assembly. This preliminary structural preparation ensures proper alignment is maintained throughout the installation process without requiring precise braze operations
Solution Approach 2:
The patent replaces the thermal-mechanical braze attachment system with a purely mechanical retention system using the heater coil structure. This substitution provides more predictable and precise alignment control through mechanical geometry rather than thermal process variability
3Ease of manufacture
If low temperature braze operation is used, then the water dam can be installed on the heater, but the process complexity increases due to additional braze steps
Solution Approach 1:
The patent combines the water dam retention function with the heater coil structure itself. The coil serves dual purposes as both the heating element and the mechanical retention structure, eliminating the need for separate braze operations and reducing overall process complexity
Solution Approach 2:
The heater coil is designed to perform multiple functions: providing thermal heating and simultaneously providing mechanical retention and alignment for the water dam. This multi-functionality reduces the number of separate components and assembly steps required
Data Source
AI summary
In accordance with at least one aspect of this disclosure, an air data probe includes, an outer shell defining an airflow path from an inlet at a proximal end thereof to a distal end thereof and a heater configured to be installed within the outer shell an in the airflow path, the water dam comprising, one or more sensing elements at a distal end thereof. The system also includes, a water dam disposed on or in the heater winding and between a proximal end and distal end of the heater winding configured to impede a flow of water droplets and ice crystals to permit proper drain hole operation, prevent moisture buildup in rear areas of the probe and pressure lines, and prevent interaction of the flow of water and the one or more sensing elements. The water dam is configured to mechanically stabilize itself on or in the heater winding during installation of the heater winding and water dam into the outer shell.