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September 7, 2022

3 ways advanced DAQ solutions help the aviation industry transition to a sustainable future

By 2050 we need to become a carbon-neutral society, and the aviation sector needs to contribute. While flying less can help reduce emissions, we have options for cleaner air travel. For one, we could power our flight with electricity or hydrogen, which are no longer ideas in some futuristic science fiction novel. Rather, they are on the brink of generating a shift in aviation technology.

1. High-voltage isolation modules for electric & hybrid-electric propulsion testing

Electric and hybrid-electric propulsion is one of the hottest topics in aerospace. Electrical propulsion has the potential to make flights quieter with reduced emissions, safer with reduced costs, and could open up new segments of aviation; Unmanned Aerial Systems (UAS), Urban Air Mobility (UAM) platforms, and other small passenger and cargo aircraft are all good candidates. The industry must close the technology gap in electrical propulsion, where there are currently several barriers that aircraft companies are working on overcoming. These include battery density, efficient electrical systems, effective system integration, and effective regulation/airworthiness solutions to enable new propulsion systems and architectures.

Lilium Jet - the first eVTOL - made its maiden flight in May 2019 (Source by Lilium GmbH)

The Q.series X data acquisition product line from Gantner Instruments includes a variety of high-voltage isolation measurement modules to support customers with electric motor & inverter testing, battery performance & charge testing, mechanical & vibration testing, and propulsion system integration testing. The high-voltage isolation modules come with 1200 VDC triple galvanic isolation and can measure voltage, current, RTD, thermocouple, IEPE, and strain gage sensors up to 100 kHz.

2. Cryogenic measurement technology supporting the development of hydrogen-powered aircraft

Electric propulsion is not feasible for large commercial airplanes in the short and medium term because the batteries and wiring would be too heavy. Not to mention that these batteries would generate a lot of heat and offer short service life in terms of the number of flight hours of a jet airliner. Instead, hydrogen-powered aircraft is one of the most promising technologies for large commercial aviation. When generated from renewable energy sources, it emits zero CO2. Significantly, it delivers approximately three times the energy per unit mass of conventional kerosine fuel and more than 100 times that of lithium-ion batteries. 

3D rendering of zero-emission aircraft with two hybrid-hydrogen turbofan engines

However, storing hydrogen onboard an aircraft poses several challenges. A growing number of aircraft companies are working on cryogenic hydrogen tank designs, as cryotank storage is considered one of the best options for its storage. Hydrogen turns into a liquid when cooled to a temperature below -253 °C (-423 °F). The properties of liquid hydrogen enable significant increases in density over high-pressure gas storage, as well as reduced tank mass due to lower pressure operation, but does impose some significant operational constraints on the fuel system:

  • It requires an airtight insulation system to reduce the boil-off of the liquid hydrogen and maintain it at cryogenic temperatures.
  • Liquid hydrogen handling requires specialized equipment and procedures.
  • The fuel tanks must be maintained at a constant pressure to minimize boil-off.
  • Liquid hydrogen tanks and lines must be sealed off from the atmosphere (if air enters the tanks, it will freeze solid and can block the flow lines).

 

The range of Q.series X A105 CR measurement modules has been designed for use with cryogenic temperature sensors, like Cernox® or TVO. The module provides ultralow sensor excitation to minimize measurement error due to the sensor self-heating while maintaining a good signal-to-noise ratio. Furthermore, the module comes with a sensor-specific linearization table to compensate for the high non-linearity of cryogenic temperature sensors.

In addition, a variant of our renowned A101 measurement module has been introduced for measuring strain in a low-temperature environment. The module comes with smart ON/OFF switching of the bridge excitation voltage to avoid sensor self-heating and a 3-step measurement to correct the influence of thermoelectric voltage when using cryogenic wiring.

3. Strain measurement for characterization of lightweight composite structures

Weight is the enemy of all things in aerospace; the more weight you add to an aircraft, the more fuel you need to fly it. The aerospace industry has long endeavored to make aircraft designs lighter. With lighter aircraft, it is possible to reduce fuel consumption and CO2 emissions and, therefore, the environmental impact. New carbon fiber composite fabrication techniques like 3D printing or automated fiber placement enable the design and manufacture of complex lightweight structures stronger than traditional aluminum and provide a smoother, more aerodynamic surface, increasing performance and fuel efficiency. In addition to airframers, the aero engine sector is investing heavily to replace metallic materials such as titanium with carbon fiber composite material that can be used at temperatures over 200 °C (392 °F), a temperature range at which titanium is currently used.

Composite fan blades on the General Electric GEnx-1B result in lighter and more efficient engines

The advantage of tailoring composite structures to a wide range of performance criteria makes it difficult to predict part performance. To meet that challenge, aircraft engineers are moving to finite element analysis (FEA) methods and FE-based simulation, also known as virtual testing. However, composite manufacturing techniques are frontrunning the analysis capabilities. There is not enough real test data to benchmark the virtual models, increasing uncertainties and reducing confidence in design. More physical structural testing is needed to measure the ‘unknown.’ The virtual test models are then validated and adjusted against the values gained from the physical tests.

The ability to accurately validate finite element models raises the need for precise microstrain measurement to single-digit accuracy. Gantner Instrument’s range of 24-bit strain gage amplifiers is specially designed to meet these challenging requirements. In combination with a high-stability bridge completion resistor, low bridge excitation avoids substantial measurement errors due to temperature variations in the measurement chain. This blog post presents eight helpful tips when choosing a strain gage amplifier for your aerospace structural test setup.

Gantner Instruments’ measurement experts are committed to providing best-in-class, individualized sales and technical application support. Our application support is free and available without barriers to existing and potential customers. Let us help you transition smoothly to a sustainable future!

We are happy to work with you to find the ideal data acquisition solution for your requirements!

 

Talk to our experts, and you will learn:

  • Why high-voltage isolation is a must in electric propulsion testing
  • How to solve the challenges of measurement in a cryogenic environment
  • How to select the best strain gage amplifier for your structural test

Author: Stephan Ploegman

Stephan Ploegman is Gantner Instruments business developer in Aerospace & Structural Testing

Do you have any questions? Please contact our measurement technology experts: