Hybrid Aircraft Ground Effect Estimation Method
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Solution Overview
Problem
Current methods for assessing aerodynamic ground effect on aircraft are plagued by inaccurate and unreliable measurements due to high correction levels in wind tunnel tests and unreliable digital simulations, especially at heights close to the ground where the effect is most intense, and require extrapolation that lacks physical accuracy.
Innovation Solution
A hybrid method that subdivides the range of heights into sets, using wind tunnel tests for intermediate heights and digital simulation for low and high heights, allowing for the most accurate and reliable determination of aerodynamic coefficients by combining experimental and computational methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wind tunnel tests are used to measure aerodynamic coefficients at low heights, then measurement data can be obtained, but the correction levels become excessively high making measurements inaccurate and unreliable
Solution Approach 1:
The height range is divided into three consecutive sets: low heights (digital simulation), intermediate heights (wind tunnel tests), and high heights (digital simulation). This segmentation allows each method to be applied where it is most effective, avoiding the use of wind tunnel tests at low heights where corrections are excessively high and measurements become unreliable.
2Measurement precision
If the model is brought close to the floor to measure ground effect, then more accurate ground effect data can be obtained, but the model may be damaged by vibrations from the airstream
Solution Approach 1:
Digital simulation acts as an intermediary method to obtain ground effect data at low heights where physical models cannot safely operate. The simulation reproduces the physical reality of air flow around the aircraft at heights below the minimum safety height, eliminating the risk of model damage while providing accurate ground effect measurements.
3Adaptability or versatility
If digital simulation is used to assess ground effect, then measurements can be obtained at all heights, but the simulation is not currently reliable or accurate enough
Solution Approach 1:
Different methods are applied to different height ranges based on their local strengths. Digital simulation is used where it provides sufficient accuracy (high heights and low heights), while wind tunnel tests are used in the intermediate range where they provide better reliability. This local optimization ensures the most accurate results are obtained for each height range.
4Productivity
If extrapolation is used to estimate ground effect at very low heights, then data can be obtained beyond the minimum safety height, but the extrapolation lacks physical accuracy
Solution Approach 1:
Mathematical extrapolation is replaced with digital simulation that reproduces the physical reality of air flow. Instead of using mathematical models to extend beyond measured data, the simulation directly computes the aerodynamic coefficients at low heights by modeling the actual fluid dynamics, providing physically accurate results.
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 hybrid approach reduces the weight of wall corrections, introduces physical principles into ground effect assessment, and provides accurate measurements across the entire range of heights, replacing mathematical extrapolation with computational estimates, while being easily integratable with existing processes.
Implementation Method 1
perform an experimental assessment of said aerodynamic coefficient by producing a model of said aircraft and by placing said model in a wind tunnel airstream limited by a floor simulating the ground
Implementation Method 2
digital simulation reproducing by computation the physical reality of the flow of air around said aircraft
Data Source
AI summary
A method for assessing the aerodynamic ground effects on an aircraft. The method includes determining the variation of at least one aerodynamic coefficient of the aircraft as a function of the height for a range of heights extending from an aerodynamically infinite height to a zero height. In the method, (i) the range of heights is subdivided into at least two consecutive sets of heights; (ii) for one of the sets of heights, the variation of said aerodynamic coefficient is determined by wind tunnel tests using a model of the aircraft; and (iii) for the other of the sets of heights, the variation of said aerodynamic coefficient is determined by digital simulation reproducing by computation the physical reality of the air flow around said aircraft.