Boundary Layer Flow Sensor with Retractable Pressure Port
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Solution Overview
Problem
Conventional methods for determining laminar or turbulent airflow over aerodynamic surfaces are cumbersome, impractical for flight operations, and create additional drag, lacking the robustness needed for continuous use.
Innovation Solution
A boundary layer flow sensor with a reconfigurable pressure port that can be mounted within an aerodynamic surface, transitioning between open and closed states to expose or decouple from the airflow, allowing for measurement of total and static pressures to determine flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement techniques (infrared camera, hot film, pressure tube) are used to determine airflow characteristics, then measurement capability is provided, but device complexity and drag increase while robustness decreases
Solution Approach 1:
The pressure sensing functionality is extracted from complex external measurement systems (infrared cameras, hot films) and integrated directly into a simple pressure tube mounted within the aerodynamic surface. This extraction reduces device complexity while maintaining measurement capability through a minimalist sensor design that uses only a pressure port and tube configuration.
Solution Approach 2:
Instead of using complex direct measurement devices, the patent uses a simplified pressure tube that copies the essential measurement function (pressure detection) without requiring the complex infrastructure of infrared cameras or hot film systems. The pressure tube provides a analogous but simpler measurement approach that achieves the same informational goal with reduced complexity.
2Measurement precision
If pressure tubes are mounted on the aerodynamic surface to measure total pressure, then airflow measurement is enabled, but additional drag is created
Solution Approach 1:
The pressure tube is positioned with its opening at a specific location within the boundary layer (at a distance of 0.05c to 0.20c from the surface) where it can measure total pressure without protruding into the main airflow. This localized positioning provides the necessary measurement capability while minimizing the tube's interference with the overall airflow and reducing drag generation.
Solution Approach 2:
The pressure measurement function is achieved by positioning the pressure port in a specific spatial dimension within the boundary layer rather than having the tube protrude outward. By utilizing the vertical dimension within the boundary layer thickness, the system obtains measurement capability without adding external protrusions that would increase drag.
3Productivity
If the sensor remains exposed to measure airflow continuously, then measurement capability is maintained, but contamination and durability issues arise
Solution Approach 1:
The pressure port is designed to be dynamically configurable between open and closed states. The movable cover or door mechanism allows the port to open for measurement and close for protection, enabling the sensor to adapt its exposure level based on operational needs. This dynamic configuration maintains measurement capability when needed while protecting against contamination during storage or non-measurement periods.
Solution Approach 2:
The movable cover or door is positioned in advance to close over the pressure port when measurement is not required, preventing contamination before it can occur. This preliminary protective action ensures that the sensor remains clean and durable during periods when continuous measurement is not needed, while allowing quick opening when measurement is required.
4Measurement precision
If the pressure port is always open for measurement, then measurement accuracy is maintained, but the sensor creates flow disruption and drag
Solution Approach 1:
The pressure port is positioned locally within the boundary layer at a specific distance from the surface (0.05c to 0.20c), where it can obtain accurate pressure measurements without protruding into the main airflow. This localized positioning within the boundary layer allows the port to be open for measurement while minimizing disruption to the overall aerodynamic surface shape and flow patterns.
Solution Approach 2:
The measurement function is achieved by utilizing the vertical dimension within the boundary layer rather than having the pressure port protrude outward from the surface. By positioning the open port within the thickness of the boundary layer, the system maintains aerodynamic surface smoothness in the external flow while enabling pressure measurement through the boundary layer interface.
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
Enables accurate determination of laminar or turbulent flow without disrupting the airflow or succumbing to contamination, while maintaining a flush configuration to prevent drag and ensure durability during flight operations.
Implementation Method 1
The airflow at the aerodynamic surface may be thought of as having zero velocity at the precise location abutting the surface due to the viscosity at the surface, speeding up to the mean velocity of the ambient airflow at a distance from the surface. The airflow within this distance defines the boundary layer.
Data Source
AI summary
Apparatus and methods described herein provide for boundary layer flow sensor and corresponding determination of the flow characteristics of an ambient airflow over an aerodynamic surface. According to one aspect of the disclosure provided herein, the boundary layer flow sensor includes a body configured for mounting within or below the aerodynamic surface, a pressure port configurable between an open state for taking pressure measurements within the boundary layer of the ambient airflow and a closed state that protects the pressure port from contaminants when not in use.