Beckmann, Simon

Hoff, Tim

Rodeck, Rebecca

Wende, Gerko

Wicke, Kai

Institute of Transport Research:Publications

Smart Sensor Network for Hydrogen Detection andLocalisation in Aircraft EnvironmentsTim Hoff*, Simon Beckmann*, Kai Wicke*, Rebecca Rodeck* and Gerko Wende**German Aerospace Center (DLR), Institute of Maintenance, Repair and Overhaul, Hamburg, 21129, GermanyHydrogen is often considered as one of the mostpromising power sources for meeting the aviation sec-tor’s long-term decarbonization goals. Practitionersand researchers are therefore actively investigatingwhether it is possible to use hydrogen as a powersource for aircraft in order to create sustainablealternatives to conventional fossil fuels. One majorchallenge in doing so is its high explosiveness, as ahydrogen-air mixture is ignitable between 4 and 75%hydrogen in air by volume. This explosiveness leadsto safety concerns especially regarding leakages of allhydrogen-carrying systems and is a major challenge inits use as an energy carrier in aviation.Therefore, the goal of this ongoing study is todevelop a new hydrogen sensor monitoring concept insuch a way that not only safe operation of possiblehydrogen systems in aircraft is guaranteed, but at thesame time the leakage can be localized as quickly aspossible in the event of uncontrolled hydrogen emis-sions. The measurement method should be flexibleand adapt to the different environmental conditionsto which aircraft are exposed.To achieve this, a digital, bus-based smart sensornetwork was developed. It combines a multitude ofsensors such as gas-, humidity-, temperature and airflow sensors, each of them extended with a dedicatedcomputing unit. These controllers can be specificallyprogrammed to the assigned sensor and their currentstatus, operating conditions, measurement require-ments and positioning and can be reconfigured by amaster command control unit at any time. Each ofthese small computing units is linked to each othervia a bus interface. Since data is almost exclusivelysent on the bus communication line in the case ofan event, there is a high degree of freedom andflexibility in the data communication. Such an eventwould primarily be the detection of a a hydrogenconcentration exceeding a predefined limit. In caseof an event, the master command control unit canrequest the raw data of the current measurement, aswell as past recorded data.The localization of a possible leakage is achievedby post-processing the generated data. Using timedeviations of the hydrogen detection of each sensorand knowledge about its positioning, it is possibleto use a number of methods to localize the leakage.Potential methods could include those rooted in ma-chine learning or geometry-based approaches. Usageof additional data such as air speeds, generated bythe air flow sensors, can be used to optimize the result.The proposed concept has several advantageoususe cases. For example, through local digitization,parameterisation and subsequent signal analysis, thestatus of all sensors can be monitored with a simpletraffic light display. It also enables to utilize themaximum number of sensor nodes (125) per bus,adding flexibility to add or remove sensors. Further-more, to avoid distorting recorded data, changes inthe environment (e.g. change of flight phase) canbe communicated to the smart sensors so that theyre-calibrate themselves in a decentralized manner.The localization of the leakage decreases repair times,as manual search can be prevented.These use cases make the proposed smart sensor net-work stand out from other state of the art hydrogenmonitoring systems. However, additional work has tobe performed in order to test the system, develop so-phisticated post-processing methods and identify andchallenge individual use cases. The main focus onfurther research will lay on the tests in a small scalelabrotary environment as well as the implementationof the system in the ”Hydrogen Aviation Labs” grounddemonstrator in the midterm future. This is performedwith the thought to develop a flexible but expedientsystem that enables a safe operation of hydrogen sys-tems on board of aircraft, ultimately supporting theimplementation of hydrogen in aviation in order toachieve more sustainable air flight.2

Smartes Sensornetz zur Detektion und Lokalisation von Wasserstoffleckagen in Flugzeugumgebungen

https://elib.dlr.de/198465/1/DLRK-Abstract_Hoff.pdf

Smartes Sensornetz zur Detektion und Lokalisation von Wasserstoffleckagen in Flugzeugumgebungen

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Institute of Transport Research:Publications