Ultrasonic Fuel Flow Meter Buffer Rod Structure for Harsh Conditions
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Solution Overview
Problem
Existing ultrasonic flow meters face challenges in maintaining accuracy and survivability under extreme fluid environmental conditions, such as high pressures and temperatures, and varying fluid densities, particularly in applications like aircraft gas turbine engines, where they are required to operate over a wide turndown ratio and maintain dynamic accuracy with high update rates.
Innovation Solution
The design incorporates a sensor housing with specific cross-sectional areas, buffer rods, and acoustic transceiver elements configured to emit and detect ultrasonic waves, using matching layers and buffer rods to protect the transceiver from fluid exposure, while determining fluid properties through time-of-flight measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the acoustic transceiver element is directly exposed to the fluid, then the measurement function can be performed, but the reliability and survivability under extreme fluid environmental conditions (high pressure, temperature, varying density) deteriorates
Solution Approach 1:
The sensor housing is divided into multiple axial portions (first axial sensor housing portion, second axial sensor housing portion) with different cross-sectional areas. The buffer rods are segmented into multiple sections (first axial buffer portion, second axial buffer portion, third axial buffer portion) with varying cross-sectional areas. This segmentation allows each portion to be optimized for its specific function while collectively providing protection against extreme environmental conditions.
Solution Approach 2:
Buffer rods are introduced as intermediary elements between the acoustic transceiver element and the fluid environment. These buffer rods transmit acoustic waves while protecting the transceiver from direct exposure to extreme fluid conditions (high pressure, temperature, varying density). The buffer rods act as a mediator that enables both measurement functionality and environmental protection.
2Reliability
If the sensor housing cross-sectional area is increased to protect the transceiver, then the reliability improves, but the device complexity and size increase
Solution Approach 1:
The sensor housing and buffer rods feature varying cross-sectional areas at different axial positions. The first axial sensor housing portion has a first cross-sectional area, while the second axial sensor housing portion has a second cross-sectional area that is larger. Similarly, the buffer rods have different cross-sectional areas in different axial portions. This local quality variation provides enhanced protection where needed while minimizing overall device complexity and size.
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 system provides improved environmental survivability, accuracy, and integral fluid density sensing, maintaining performance across wide temperature and pressure ranges, and is unaffected by fluid dynamics, with update rates of 100 Hz or greater.
Implementation Method 1
an acoustic transceiver element acoustically mated to the second axial end and the third axial end. The acoustic transceiver element can be configured to emit a vibration having a predetermined wavelength (λ)
Implementation Method 2
determining fluid properties through time-of-flight measurements
Implementation Method 3
The first axial buffer portion can have a first cross-sectional area, a second axial buffer portion can have a second cross-sectional area that is larger than the first cross-sectional area, and the third axial buffer portion can have a third cross-sectional area that is smaller than the second cross-sectional area
Data Source
AI summary
The subject matter of this specification can be embodied in, among other things, a sensor that includes a first axial sensor housing portion having a first cross-sectional area, a second axial sensor housing portion arranged adjacent to the first axial sensor housing portion along the sensor axis and having a second cross-sectional area larger than the first cross-sectional area, and a face extending from the interior surface of the first axial sensor housing portion to the interior surface of the second axial sensor housing portion, a first buffer rod within the first axial sensor housing portion and having a first axial end and a second axial end, a second buffer rod within the second axial sensor housing portion and abutting the face, and having a third axial end and a fourth axial end, and an acoustic transceiver element acoustically mated to the second axial end and the third axial end.