Institute of Aircraft Production Technology

Researching an optical leakage sensor system

In the aviation industry, new drive concepts will be used in the upcoming years to improve the CO2 balance, with the aim of using completely renewable energy in the future. Flight operations with hydrogen (H2) offer advantages and are currently being pursued as the fuel of the future, but this requires suitable MRO processes (Maintenance, Repair and Overhaul) for safety concepts in order to be able to handle the highly volatile and explosive gas. It is crucial to detect any leaks that occur in the aircraft or at fuel systems. However, due to the special properties of hydrogen, conventionally available industrial approaches using imaging processes cannot be transferred to MRO processes or can only be inadequately applied.

In the HydroLeak project, an optical detection system in the form of a handheld device is being developed to carry out a manual inspection process assisted by visual user feedback. It is based on the Background-Oriented Schlieren (BOS) technique and allows rapid detection and three-dimensional localization of H2 leaks and their evaluation. A camera image is evaluated in real time and enriched with visual information and displayed on a screen. The underlying analysis methods are supported by both AI and information from the digital twin of the hydrogen system. The bidirectional coupling of the local data with the digital twin also allows data exchange to specify and document the leak in the context of a higher-level system model.

The BOS technology allows the use of simple camera technology; the complex analyzes are provided by optimized software. This leads to high availability, relative to other optical detection methods, and low costs. Given the increasing importance of hydrogen as a fuel for aviation, this process is particularly interesting for the maintenance of aircraft tank structures as well as the supply infrastructure at the airport. In addition, this process not only enables the detection of hydrogen, so that there are also a wide range of utilization options for other fields of application in which the detection of other gases is relevant. The system can also be used by laypeople because the information is easily visible on a screen. Detected leaks can be immediately digitized using the device and embedded in a digital twin in order to meet the extensive safety, quality and documentation requirements of the aviation industry.

The IFPT sub-project addresses the detection of gas leaks using suitable algorithms. First, the boundary conditions are analyzed and requirements are derived. When selecting and developing algorithms for detection or localization, existing BOS techniques known from the literature must be used. Following localization, options for AI-based quantification will also be investigated. The information generated should ultimately result in a digital twin. The IFPT is developing a suitable test stand to investigate and develop BOS technology. Figure 1 shows process steps of a possible future H2 detection.

Figure 1: Process steps for the localization and analysis of leaks using the BOS-technique: [1] detection and localization within the measurement range [2] risk assesment by quantifiying the leak [3] global localization by scanning a QR code

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Contact person at the institute:  Lukas Bath