Flow-through Transducer for Wind Tunnel Analysis

Mechanical and Fluid Systems

Flow-through Transducer for Wind Tunnel Analysis (LAR-TOPS-344)

Six-component integral flow-through balance incorporating axial force measurement

Overview

Existing integral flow-through balances have been limited to five-component force and moment measurements (Normal and Side force; Pitch, Yaw, and Rolling moment) – excluding a 6th desired force measurement: Axial force. To enable key aeroscience R&D applications, NASA’s Langley Research Center has developed a single-piece flow-through transducer design capable of measuring all six components – adding in the Axial force measurement. Compared to NASA’s technology, conventional flow-around designs (which require bellows and provide only a structurally parallel flow path around the balance) are typically restricted to low pressure applications; in contrast, NASA’s technology can accommodate both high- and low-pressure requirements, while eliminating the employment of bellows (which are complex to install and maintain, susceptible to leakage, highly flow sensitive, and lead to hysteresis effects). NASA’s rigid and stable integral flow-through balance offers repeatable and high-quality measurements that are significantly less dependent on pressure and flow rate affects.

The Technology

Axial force is a key parameter for many aeroscience R&D applications. Axial force is the dominant component used to measure aircraft drag (for fuel efficiency purposes) and provides important control information (such as vehicle deceleration rate). Integration of Axial force measurement into this design enables a direct measure of the drag force, while simultaneously providing a fluid flow path for powered simulation in wind tunnel testing. Current state-of-the art alternatives (i.e., flow-through balances without axial force) either require investigators to infer the drag force by integrating pressure taps on the test article (which further increases axial force measurement uncertainty) or run a redundant, second wind tunnel entry with a standard six-component balance without the flow-through capability (which is not desirable because they are expensive, time consuming, and impede efficiency). While NASA’s flow-through transducer technology could be manufactured using conventional fabrication methods, additive manufacturing is expected to be preferred as it enables relatively simple incorporation of the flow-through axial element into the design without increasing manufacturing complexity or costs.

The upper image shows a prototype of the six-component integral flow-through balance concept manufactured using additive manufacturing; in this prototype, the balance was manufactured out of a transparent plastic so the internal flow paths (painted red for visualization purposes) could be visualized from outside the part. The lower image shows an additive metal prototype which is expected to be used to enable timely and affordable manufacture of a functional part.

Benefits

Incorporates Axial force into a single-piece flow through balance design.
May enable new class of force transducers: Design can measure forces over different ranges based on the modulus of the fluid (can be variable viscosity or modulus-controlled fluid) stored inside the transducer.
Works in variable pressure and temperature environments: Accurate in high- and low-pressure and extreme temperature environments.
Faster and lower-cost manufacturing: The transducer can be additively manufactured in days, saving time and costs.
Eliminates need for bellows: Avoiding key downsides of bellows.

Applications

Force measurement: For example in wind tunnel testing, supports tests requiring fluids at high pressure (i.e., enabling direct measurement of supersonic retropropulsion forces), systems tuning (controlling the static and/or dynamic structural response via active stiffness and dampening adjustment), and a range of other applications.

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Technology Details

Category Mechanical and Fluid Systems

Reference Number LAR-TOPS-344

Case Number(s) LAR-19817-1

Patent(s) (pop-up blockers must be disabled) 11,802,803

Papers

Tags:

Flow-through Flow through Aeroscience Aersospace Automotive Wind tunnel Balance Fluid dynamics Test equipment Metrology Aerodynamics Force Moment Additive manufacturing 3D printing

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