Wind Flow Sensing System Correcting Homogeneous Velocity Bias
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Solution Overview
Problem
Current remote sensing systems, such as LiDAR, face challenges in accurately measuring wind flow over complex terrain due to the homogeneous velocity assumption, leading to errors in horizontal and vertical velocity determination, especially near undulating terrains or urban structures.
Innovation Solution
The system employs computational fluid dynamics (CFD) to estimate wind velocity fields by determining the horizontal derivative of vertical velocity, which corrects the bias caused by the homogeneous velocity assumption, using a direct-adjoint looping framework to optimize operating parameters and enforce incompressibility, thereby improving the accuracy of wind flow sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If geometric models with homogeneous velocity assumption are used, then the system is simple to operate, but measurement precision deteriorates over complex terrain
Solution Approach 1:
The patent transforms the calculation approach by introducing vertical velocity as a new parameter and using its horizontal derivative to correct the homogeneous velocity assumption. This changes the fundamental parameters used in geometric models from only horizontal velocity components to include vertical velocity effects, thereby improving measurement precision while maintaining operational simplicity through automated correction algorithms.
Solution Approach 2:
The patent replaces the purely geometric calculation model with a hybrid approach that incorporates fluid dynamic principles. By substituting the mechanical/geometric assumption of homogeneity with a model that accounts for vertical velocity gradients, the system achieves higher accuracy without significantly increasing operational complexity through automated CFD-based corrections.
2Measurement precision
If CFD simulation is used to correct homogeneous velocity assumption, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies partial CFD simulation only where needed - specifically for calculating the horizontal derivative of vertical velocity to correct the homogeneous assumption - rather than performing full CFD simulations throughout the entire measurement volume. This selective application of complex processing achieves measurement precision improvement while limiting the increase in device complexity to only the necessary correction calculations.
3Productivity
If homogeneous velocity assumption is applied, then productivity is high due to simple calculations, but measurement precision deteriorates in complex terrain
Solution Approach 1:
The patent performs preliminary CFD-based calculations to establish the horizontal derivative of vertical velocity before applying the correction to the main wind velocity measurements. This preliminary action allows the system to maintain high productivity during routine operations while periodically applying precision corrections, thereby achieving both fast calculation speeds and improved accuracy over complex terrain.
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
This approach enhances the accuracy of wind flow sensing over complex terrains by reducing errors associated with the homogeneous velocity assumption, achieving a target accuracy in velocity field determination using radial velocity measurements.
Implementation Method 1
The beams are subjected to scattering effects in the atmosphere, due in particular to the inhomogeneities encountered (aerosols, particles, variations in refractive indices for electromagnetic waves)
Implementation Method 2
When they are scattered in air masses or moving particles, these beams of waves also undergo a frequency shift by the Doppler effect
Implementation Method 3
The distance along the measurement axis of the detectors at which scattering occurred can then be calculated, for example by a method of measuring the time of flight
Implementation Method 4
The distance along the measurement axis of the detectors at which scattering occurred can then be calculated, for example by a method of phase shift measurement by interferometry
Data Source
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AI summary
A wind flow sensing system determines a first approximation of the velocity field at each of the altitudes by simulating computational fluid dynamics (CFD) of the wind flow with operating parameters reducing a cost function of a weighted combination of errors, determines a horizontal derivative of vertical velocity at each of the altitudes from the first approximation of the velocity fields, and determines a second approximation of the velocity fields using geometric relationships between a velocity field for each of the altitudes, projections of the measurements of radial velocities on the three-dimensional axes, and the horizontal derivative of vertical velocity for the corresponding velocity field. In the cost function of the CFD, each error corresponds to one of the altitudes and includes a difference between measured velocities at the line-of-site points at the corresponding altitude and simulated velocities at the line-of-site points simulated by the CFD for the corresponding altitude. At least some errors in the weighted combination have different weights.