Sonic Anemometer Low-Pressure Wind Speed Measurement
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Solution Overview
Problem
Sonic anemometers face challenges in accurately measuring wind speeds in low-pressure environments, such as those found on Mars, due to issues like radiative heating, low convective heat losses, and sensitivity to temperature and pressure fluctuations, which affect the accuracy and precision of traditional measurement methods.
Innovation Solution
A sonic anemometer system utilizing multiple transducer pairs that measure bi-directional acoustic data to calculate flow speed, with a controller configured to correct for temperature, pressure, and wake effects using a system model, enabling precise measurements in low-pressure conditions by determining phase lags and flight times, and generating reports on flow speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional hot wire/film systems are used for wind speed measurement, then the measurement mechanism is simple, but the accuracy and precision deteriorate in low-pressure environments
Solution Approach 1:
The patent replaces traditional mechanical hot wire/film anemometers with a sonic anemometer system that uses ultrasonic transducers and acoustic wave propagation measurements. This substitution eliminates the mechanical heating elements that fail in low-pressure environments, using instead the propagation of sound waves through the atmosphere to measure wind speed, thereby achieving accurate measurements in low-pressure conditions without relying on thermal convection mechanisms
Solution Approach 2:
The patent changes the measurement parameter from thermal convection (hot wire/film) to acoustic wave propagation (sonic transducers). By measuring the time of flight and phase differences of ultrasonic waves traveling through the atmosphere, the system adapts to low-pressure environments where thermal convection is insufficient, fundamentally changing the physical parameter used for wind speed measurement
2Measurement precision
If sonic anemometer system is used, then measurement accuracy in low-pressure environments improves, but device complexity increases
Solution Approach 1:
The patent implements a controller that performs multiple functions: it measures time of flight, calculates phase differences, compensates for temperature and pressure effects, and generates flow speed measurements. This multi-functional controller consolidates what would otherwise require separate systems, reducing overall device complexity while maintaining high measurement accuracy in low-pressure environments
Solution Approach 2:
The patent incorporates feedback mechanisms where the controller continuously monitors environmental conditions (temperature, pressure) and adjusts measurements accordingly. The system uses feedback loops to compensate for environmental variations affecting acoustic wave propagation, ensuring accurate wind speed measurements by dynamically adjusting for temperature and pressure effects on sound speed
3Reliability
If multiple transducer pairs are used for bi-directional measurements, then measurement reliability improves, but device complexity increases
Solution Approach 1:
The patent combines multiple transducer pairs into an integrated sonic anemometer system where all transducers are coordinated by a single controller. The bi-directional measurements from multiple transducer pairs are merged and processed together to calculate three-dimensional flow vectors, achieving high reliability through redundant measurements while consolidating control functions to manage system complexity
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 accurate and precise wind speed measurements in low-pressure environments, offering 20 times improvement over traditional hot wire/film systems, with sensitivity to winds as small as 5 cm/s and independent measurements at 20 Hz, suitable for planetary science applications and high-altitude measurements.
Implementation Method 1
A sonic anemometer uses ultrasonic sound waves to determine wind speed. Broadly, wind speed can be determined in real-time by measuring the effect of the wind on the speed of sound waves traveling between a pair of transducers.
Implementation Method 2
The controller is further configured to measure phase lags corresponding to the bi-directional acoustic data, and determine bi-directional flight times using the phase lags.
Data Source
AI summary
A method of determining flow speed in a low pressure environment. The method includes obtaining bi-directional acoustic data from a plurality of transducer pairs as a fluid moves relative to the plurality of transducer pairs. The method further includes measuring phase lags corresponding to the bi-directional acoustic data, and determining bi-directional flight times using the phase lags. Additionally, the method includes calculating a flow speed of the fluid corresponding to each transducer pair from the bi-directional flight times. The method includes correcting for at least one of temperature effects, pressure effects, and wake effects, using a system model. The method further includes generating a report including the flow speed of the fluid.