3D scanning has established itself as new method to document the final ice accretion on test objects (e.g. components or systems of aircraft, helicopter, and UAV) after icing wind tunnel test runs. The final ice shapes are quite complex and can differ significantly in their size and appearance because the icing process is influenced by many variables. To better understand the icing process and the impact of the final ice accretion on the flight characteristics of the respective aircraft, an accurate 3D scan is of importance. Nevertheless, special software tools are also required to process and evaluate the generated 3D data to investigate the parameters of interest, e.g. ice thickness and ice surface roughness.
This report provides an overview and summarizes the activities performed at the Austrian Institute for Icing Sciences (AIIS) as part of WP4 in the ICE GENESIS project.
The presented work was performed between January 2019 and December 2020 in the scope of Task 4.5. The main objective of the task was to select and optimize a 3D scanning system for icing wind tunnel test facilities capable to be used for experiments and different test specimen in order to characterize the following features:
- 2D contours
- 3D ice shape
- surface roughness
- ice density (combined with weighing device)
In addition, an appropriate post-processing tool for the surface roughness evaluation of 3D scans was developed. Due to the nature of the performed activities, this report is divided into two parts:
Part 1: Assessment and optimization of 3D scanning system
In part one different 3D scanning systems were tested and compared to identify the most suitable device for scanning of ice shapes. Therefore, the main scanning methods, as well as the accuracy of devices and the relevant accuracy standards were reviewed. Requirements based on the scope of application were defined to select 3D scanners for preliminary testing. The focus of the preliminary testing was to test the capabilities of the devices in general with an emphasis on surface roughness measurements, handling, and data quality.
Based on the results of the preliminary testing, one 3D scanner with interchangeable laser scan unit was selected to perform a detailed analysis of its surface roughness measurement capabilities. The repeatability of the measurement results was investigated, and the scanning system was tested and optimized for use in the icing wind tunnel.
Part 2: Software evaluation tool
The software tool is required to evaluate the generated 3D data and compute the parameters of interest. In part two of the report the existing software capabilities and sample applications are presented. Thereafter, the focus is laid on the newly added capabilities for surface roughness analysis in 2D and 3D with a special emphasizes on the curvature-correction in 2D and 3D, as well as the automatic codebook-vector spacing.