Boundary Layer Probe with Obstacles for Instantaneous Flow Measurement
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Solution Overview
Problem
Existing boundary layer probes require a 360° rotation to determine flow properties near walls, making them unsuitable for instantaneous measurements and impractical for many applications due to high measurement effort and complexity.
Innovation Solution
A boundary layer probe with a measuring surface featuring elongated obstacles arranged at equidistant angular distances, allowing for the determination of flow properties like wall shear stress and flow velocity without rotating the probe, using pressure measuring points to detect local pressures and record differential pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the probe is rotated 360° to determine flow properties, then complete angular characterization is achieved, but measurement time increases and instantaneous fluctuations cannot be measured
Solution Approach 1:
The probe is divided into multiple independent pressure measuring points arranged at different angular positions around the obstacle. Each pressure point independently measures local pressure, eliminating the need for rotational movement while maintaining complete angular characterization capability.
Solution Approach 2:
The measurement approach transitions from temporal dimension (rotating probe over time) to spatial dimension (multiple fixed pressure points at different angles). This allows simultaneous measurement of flow properties at all angular positions without rotation.
2Measurement precision
If the probe is rotated 360° in equidistant steps, then angle characteristic curve is obtained, but measurement complexity and setup complexity increase
Solution Approach 1:
The measurement system is segmented into multiple independent pressure sensing elements fixed at specific angular positions. This eliminates the need for rotational mechanisms and complex control systems while maintaining the ability to determine angle characteristics through spatial distribution of pressure measurements.
Solution Approach 2:
The mechanical rotation system is replaced with a static multi-point pressure measurement system. Flow direction and angle characteristics are determined through evaluation of pressure differences between fixed points rather than through rotational movement.
3Ease of manufacture
If a single fence obstacle is used, then the measurement principle is simple, but measurement effort and complexity remain high due to rotation requirements
Solution Approach 1:
Instead of using a single fence obstacle requiring rotation, the design employs multiple pressure measuring points distributed at different angular positions. This segmentation allows simultaneous measurement of flow properties at all angles without rotation, dramatically improving measurement efficiency while keeping individual pressure points simple in structure.
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 efficient and instantaneous measurement of fluid flow properties, including wall shear stress and flow velocity, without the need for probe rotation, suitable for higher fluid velocities where compressibility is significant, reducing measurement complexity and effort.
Implementation Method 1
An assembly of measuring obstacles is provided which are formed in the region of the measuring surface and which disrupt the fluid flow in a flow region adjacent to the measuring surface
Implementation Method 2
The boundary layer probe has pressure measuring points, each of which is radially adjacent to an associated obstacle in order to detect a local pressure in the region of the measuring surface
Data Source
AI summary
The invention relates to a boundary layer probe for determining a fluid flow, comprising a measuring surface which is formed on a probe wall and with which a fluid flow to be determined is in contact during a measuring operation. The boundary layer probe also comprises an assembly of measuring obstacles that are formed in the region of the measuring surface as obstacles which disrupt the fluid flow in a flow region adjacent to the measuring surface, each of which has an elongated obstacle course extending over a particular obstacle length, and which are arranged at substantially equidistant angular distances in the circumferential direction. The boundary layer probe additionally has pressure measuring points, each of which is radially adjacent to an associated obstacle in order to detect a local pressure in the region of the measuring surface. The invention additionally relates to a measuring assembly and to a method for determining a fluid flow.