Wind Tunnel Transducer Biasing Assembly for Environmental Compensation
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Solution Overview
Problem
Platform balances in wind tunnels face inaccuracies in measuring forces and moments due to environmental factors like temperature transients and large test specimens causing thrust loads, which affect transducer measurements.
Innovation Solution
A transducer body design featuring a support with clevis halves and a sensor body connected via flexure components and a biasing assembly, providing a bias force and improved flexibility to compensate for environmental influences and enhance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a platform balance is used to measure forces and moments in a wind tunnel, then measurement capability is provided, but measurement accuracy deteriorates due to environmental factors like temperature transients and thrust loads from large test specimens
Solution Approach 1:
The biasing assembly applies a pre-compressive force to the sensor body, creating a counterbalancing effect that offsets the harmful thrust loads generated by large test specimens. This pre-loading ensures the sensor body remains in a compressed state during operation, compensating for the adverse effects of environmental factors and maintaining measurement accuracy.
Solution Approach 2:
The biasing assembly pre-loads the sensor body with a compressive force before the actual measurement process begins. This preliminary action prepares the sensor body to withstand subsequent thrust loads from test specimens, ensuring it operates within its optimal measurement range and compensating for temperature transients and other environmental variations.
2Strength
If the sensor body is made rigid to maintain structural integrity, then strength is improved, but flexibility to compensate for environmental influences is reduced
Solution Approach 1:
The sensor body employs a composite structure where different regions have different mechanical properties. The peripheral member is designed to be relatively rigid to maintain structural integrity, while the central hub and flexure components are designed with appropriate flexibility to accommodate environmental variations. This local differentiation of mechanical properties allows the sensor body to simultaneously achieve strength and adaptability.
Solution Approach 2:
The sensor body utilizes a composite construction combining rigid peripheral members with more compliant central hub structures and flexure components. This composite approach allows different parts of the sensor body to exhibit different mechanical characteristics - rigidity where structural integrity is needed and flexibility where environmental compensation is required - thereby resolving the contradiction between strength and adaptability.
3Volume of moving object
If the peripheral member is positioned close to the clevis halves to reduce size, then compactness is improved, but the biasing assembly cannot provide adequate bias force
Solution Approach 1:
The biasing assembly is configured to apply force in a direction that is optimally oriented relative to the sensor body geometry. By carefully selecting the orientation and direction of the biasing force, adequate compressive preload can be achieved even when the peripheral member is positioned at a reduced distance from the clevis halves, maintaining compact dimensions while ensuring sufficient bias force for accurate measurements.
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 enhances measurement accuracy and stability by compensating for environmental factors and handling large test specimens, ensuring precise force and moment measurements in wind tunnel tests.
Implementation Method 1
a biasing assembly connected between the support and the sensor body and configured to provide a bias force between the sensor body and the support
Implementation Method 2
at least three flexure components couple the peripheral member to the central hub, and where the flexure components are spaced-apart from each other at generally equal angle intervals about the central hub
Data Source
AI summary
In one aspect, a transducer body, includes a support including a pair of clevis halves; and a sensor body coupled to each of the clevis halves. The sensor body is disposed between the clevis halves and includes a generally rigid peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis half, where at least three flexure components couple the peripheral member to the central hub, and where the flexure components are spaced-apart from each other at generally equal angle intervals about the central hub. A biasing assembly connected between the support and the sensor body is configured to provide a bias force between the sensor body and the support.