Fluid Flow Sensor Plates for Pulsating Air Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Prior art fluid flow detecting devices, such as thermal type air flow meters, experience decreased measurement accuracy when measuring pulsating flows due to air flow separation and velocity changes in the bypass passage, leading to measurement errors.
Innovation Solution
A fluid flow detecting apparatus with a sensor body and bypass passage is positioned between plates wider than the sensor body, allowing the sensor to accurately detect fluid characteristics by maintaining consistent main flow velocity through the inner passage, regardless of flow steadiness or pulsation, using a heater element and thermosensor to adjust heat radiation and electric current based on flow velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermal type air flow meter is used to measure pulsating flow, then the device can detect air flow rate, but measurement accuracy decreases due to air flow separation and velocity changes in the bypass passage
Solution Approach 1:
The air flow meter is divided into separate functional sections: a main flow passage for the primary air flow, a bypass passage for a portion of the air flow, and distinct sensor regions. The sensor body is segmented with the heater element and thermosensor positioned specifically within the bypass passage to isolate measurements from main flow disturbances.
Solution Approach 2:
The bypass passage acts as an intermediary channel that takes a portion of the main air flow and directs it through a controlled path containing the sensor. This intermediary structure allows the sensor to measure flow characteristics in a more stable environment, reducing the direct impact of pulsating flow and separation effects from the main passage.
2Device complexity
If air flow separation occurs on both sides of the sensor body in pulsating flow, then the device structure is simple, but the velocity of air exiting the bypass passage decreases substantially causing measurement errors
Solution Approach 1:
The plates are positioned specifically at the upstream end of the sensor body to create localized flow control exactly where needed. This local intervention modifies the flow field in the critical region without requiring complex modifications throughout the entire device structure.
Solution Approach 2:
The solution introduces a spatial dimension by adding plates that extend into the flow path from the upstream side. This dimensional addition creates a new flow control mechanism that manages separation effects in the width direction, preventing premature separation before the air enters the bypass passage.
3Ease of manufacture
If the sensor body is inserted in the air intake pipe without additional flow control structures, then the device is easy to manufacture, but measurement accuracy decreases when measuring pulsating flow
Solution Approach 1:
The plates are positioned upstream of the sensor body to pre-condition the air flow before it reaches the measurement section. This preliminary flow control prevents separation and stabilizes the flow field in advance, ensuring that the air entering the bypass passage has consistent velocity characteristics.
Solution Approach 2:
The design uses simple flat plates that replicate the function of complex flow control structures found in other flow meters. Instead of using intricate diffusers or variable geometry components, simple planar surfaces are used to achieve similar flow stabilization effects, maintaining ease of manufacture while improving measurement accuracy.
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 apparatus reduces measurement errors associated with pulsating flows by minimizing air flow separation and maintaining consistent main flow velocity, enhancing measurement accuracy and stability across different flow conditions.
Implementation Method 1
the air flow meter measures a flow rate of the air flowing through the intake pipe (i.e. an intake air flow rate) based on the amount of heat radiated from a heater element installed in the bypass passage
Implementation Method 2
thermal type air flow meters have been proposed that measure air flow rate utilizing a resistance temperature characteristic of a hot wire
Data Source
AI summary
A fluid flow detecting apparatus is disclosed for detecting a characteristic of fluid flowing in a fluid passage. The fluid flow detecting apparatus includes a sensor body that defines a bypass passage for flow of a portion the fluid flowing in the fluid passage. The apparatus also includes a sensor provided in the bypass passage for detecting the characteristic of the fluid flowing in the bypass passage and a plurality of plates. The sensor body is provided between the plurality of plates. Each of the plates has a width dimension oriented approximately along the direction of flow of fluid flowing in the fluid passage. The width of the plates is greater than a corresponding width dimension of the sensor body such that the sensor body is inside a region defined between the plates.