Handheld Current Profiler Acoustic Inversion for Shallow Water
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Solution Overview
Problem
Existing underwater acoustic measurement systems, such as single-point current meters and traditional ADCPs, are inefficient for wading discharge measurements in shallow streams due to manual operation, limited data collection, and inability to measure velocities in very shallow waters without significant unmeasured surface or bottom layers, and flow disturbance issues.
Innovation Solution
A handheld current profiler (HCP) with a transducer array that includes a horizontal beam for single-point measurements, slant beams for velocity profiling, and an upward-looking beam for surface tracking, allowing for both manual and automated operation modes based on water depth, minimizing flow disturbance and enabling measurements in as little as 3 cm of water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional down-looking ADCP is used for shallow stream measurement, then velocity profile measurement capability is provided, but significant unmeasured surface layer and bottom layer occur due to mounting depth and blanking
Solution Approach 1:
The patent inverts the traditional down-looking ADCP configuration by using an up-looking transducer that measures upward from the stream bottom. This inversion allows the measurement beam to capture the entire water column including the surface layer that was previously unmeasured by down-looking systems, while the small transducer size minimizes bottom layer interference.
Solution Approach 2:
The patent applies local quality by using a small transducer (less than 2 cm in diameter) specifically positioned at the bottom, which creates minimal disturbance to the local flow field and reduces the side lobe effect near the water surface, thereby improving measurement accuracy in the critical surface region.
2Adaptability or versatility
If a small transducer is mounted on the end of a wading rod for shallow measurement, then capability to measure in very shallow water is improved, but significant unmeasured bottom layer and side lobe effect near surface occur
Solution Approach 1:
The patent changes the key parameter of transducer size to less than 2 cm in diameter, which minimizes the blanking distance and reduces the side lobe effect. This parameter change enables accurate measurements in very shallow water (as shallow as 3 cm) while maintaining complete coverage of the water column without significant unmeasured bottom layer.
3Measurement precision
If traditional ADCPs are used in shallow waters, then velocity profile measurement is provided, but flow disturbance becomes significant
Solution Approach 1:
The patent changes the transducer size parameter to less than 2 cm in diameter, which significantly reduces the physical obstruction to water flow. This minimal intrusion design reduces flow disturbance while still enabling accurate velocity profile measurements through the entire water column.
4Ease of operation
If single-point current meter is used for discharge measurement, then operation in shallow water is possible, but manual operation and limited data collection occur
Solution Approach 1:
The patent creates a multi-functional device that combines the capabilities of a single-point current meter and a profiling ADCP into one system. The up-looking transducer can operate in single-point mode for shallow water and automatically switch to profiling mode to measure velocity at multiple depths, eliminating manual operations and providing comprehensive data collection.
Solution Approach 2:
The patent implements dynamic operation modes that automatically adjust based on water depth conditions. The system transitions from manual single-point measurement mode to automated profiling mode, dynamically adapting its measurement strategy to maximize productivity while maintaining ease of operation across varying shallow water conditions.
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 HCP efficiently measures discharge in shallow waters by reducing manual depth measurements, minimizing flow disturbance, and providing accurate velocity profiles and surface tracking, enabling continuous operation in a wide range of water depths.
Implementation Method 1
With advanced transducers that transmit sound pulses and receive resulting echoes, water velocities in individual cells in a water column can be measured. This type of measurement is known in the industry as a current profile. As described in U.S. Pat. No. 6,052,334 the use of Doppler sonar to measure currents in a fluid medium is well-established.
Data Source
AI summary
A handheld current profiler (HCP) system and method for wading discharge measurement is disclosed. The disclosed HCP has dual capabilities. It serves as a single point current meter that can measure velocity in as little as 3 cm of water. It becomes a current profiler with an additional near surface velocity measurement cell in water about 15 cm or deeper. The HCP has a surface tracking acoustic beam that measures the water level. Thus, in most cases, no manual measurements for water depth and transducer depth are required because both depths may be measured acoustically. In addition, the disclosed HCP can have a very small transducer with a form factor which can lead to minimum flow disturbance.