INTERDISCIPLINARY CONSULTING CORP — National Aeronautics and Space Administration SBIR Phase I: A1

Description

<p style="margin-left:0in; margin-right:0in">The Interdisciplinary Consulting Corporation (IC²) proposes to develop dual-axis shear stress sensors that are applicable in ground test facilities covering a large range of flow speeds in response to NASA SBIR 2018 Phase I solicitation subtopic <em>A1.08: Aeronautics Ground Test and Measurements Technologies</em>.&nbsp;The proposed sensing system addresses a critically unmet measurement need in NASA&rsquo;s technology portfolio, specifically the ability to make time-resolved, continuous, direct, two-dimensional measurements of mean and fluctuating wall shear stress in wall-bounded turbulent and transitional flows in subsonic and transonic facilities.&nbsp;The realization of this capability not only benefits advanced air vehicle development but also impacts fundamental compressible boundary layer physics research areas such as transition to turbulence in three-dimensional flows, extending the current capabilities of NASA&rsquo;s ground test facilities.</p><p style="margin-left:0in; margin-right:0in">The proposed innovation is a dual-axis, instrumentation-grade, robust, high-bandwidth, high-resolution, silicon micromachined differential capacitive shear stress sensor for subsonic and transonic applications.&nbsp;The sensor system will enable localized, <strong>non-intrusive, vector measurement of mean and fluctuating wall shear stress</strong> for characterization of complex boundary-layer flows in ground-test facilities.&nbsp;The differential capacitive measurement scheme offers high sensitivity to in-plane shear stress as well as common-mode rejection of pressure fluctuations.&nbsp;Two sets of differential capacitors provide shear stress measurement capability in two orthogonal directions to provide the wall shear stress vector.&nbsp;Backside electrical contacts using IC²&rsquo;s patent-pending fabrication and packaging process enable the sensor to remain flush with the test article surface while significantly reducing fabrication complexity and cost.&nbsp;The modeling aspects of the proposed design approach facilitate design optimization for various applications and flow conditions.</p>