You’re surrounded by a big, busy city – crowded streets and tall buildings reaching into the sky. You’re late for an appointment. But instead of getting in a car, you’re looking for your mode of transportation: an electric vertical take-off and landing aircraft (eVTOL). It’s a small aircraft that takes off and lands vertically like helicopters, uses sustainable electric propulsion systems and is designed for short to medium distances.
Although this scenario is not yet a reality, the Federal Aviation Administration (FAA) is preparing for it to become a reality by 2028. As part of this, the FAA is working to develop Advanced Air Mobility (AAM), which the agency describes as “an emerging aviation ecosystem that leverages new aircraft and a range of innovative technologies to create more efficient, sustainable and equitable transportation options.” As AAM is integrated into the National Airspace System (NAS), ensuring the safety of travelers is the FAA’s top priority and legal responsibility. This safe operation must be ensured by all companies operating in this space.
One of these companies is Alaka’i Technologies, whose mission is to change the world by revolutionizing the transportation industry. To achieve this, the company is not just developing an eVTOL aircraft. Alaka’i is developing Skai, an eVTOL aircraft that uses hydrogen fuel cells to generate the electricity that powers its engines.
Skai floats above the ground.
“Our uniqueness is that we are the only ones using hydrogen fuel cells as an energy source,” says Hugh Kelly, Marketing Director at Alaka’i. Thanks to the many advantages of hydrogen fuel cells, the Alaka’i team sees hydrogen as the ideal energy for air mobility.
Let’s take a closer look at why this work is important, the benefits of hydrogen, and how the simulation is helping the team create a more sustainable future.
The role of eVTOLs and hydrogen fuel cells in air mobility
As populations grow and cities expand, so does our need for transportation options for people and goods. In the coming years, this could put a significant strain on existing infrastructure. For example, 500 million residents of megacities are expected to have transportation problems by 2030. This is where Urban Air Mobility (UAM) comes into play.
UAM involves implementing a safe, efficient transportation system that allows us to keep pace with these demands. New technologies such as eVTOLs play an important role in UAM as they fill the gaps in aviation, from short-haul air taxis to short-haul intercity connections. As for broader AAM goals, eVTOLs can help by, for example, assisting humanitarian groups and supporting search and rescue missions.
In addition to a wide range of potential applications, eVTOLs are also beneficial from an environmental perspective because they use electrical energy. For the Alaka’i team, that electrical energy is generated by hydrogen fuel cells. The company says this unique design decision has many benefits, including:
- Almost zero CO2 emissions when the hydrogen fuel is produced using renewable energy sources. Alaka’i’s operations already use green hydrogen produced through electrolysis, an electrochemical process that uses renewable electricity to extract hydrogen from water.
- Higher efficiency. Compared to traditional combustion engines, fuel cells can be more efficient, converting the chemical energy of the fuel into electrical energy with an efficiency of over 60%.
A contour plot analyzing the mass fraction of H2.
With its design choices, the Alaka’i team aims to revolutionize the transportation industry and make Skai the most convenient, cleanest, and safest way to get from point A to B. But first, the team must optimize its design and make sure it is fully functional. And that’s where simulation comes in.
Development of a hydrogen-powered eVTOL aircraft
To bring Skai to life, Alaka’i partnered with SimuTech Group, an Ansys Apex Channel Partner, and participated in the Ansys Startup Program. As a member of the Ansys Startup Program, Alaka’i received affordable access to simulation as well as the support and training the company needed to overcome the challenges it faced in developing Skai. One of those challenges was keeping the hydrogen fuel cells cool.
The crux of this problem is simple: hydrogen fuel cells generate heat and therefore require a suitable cooling system. But solving this problem is not as simple as it sounds. Compared to combustion engines and jet engines, “fuel cells operate at lower temperatures but still generate a lot of heat,” says Behrouz Karami, simulation expert and CFD engineer at Alaka’i. This poses a challenge for cooling, as there can be a small temperature difference between the hot surface of the fuel cell and, for example, a summer environment. This smaller temperature difference makes heat transfer more difficult.
To overcome this challenge, the team turned to Ansys Fluent fluid simulation software and its polymer electrolyte membrane (PEM) fuel cell model to explore different scenarios the fuel cell might face—all “in the controlled temperature environment of our office,” Karami jokes. To accurately analyze the cooling system for Skai’s hydrogen fuel cell, these simulations included modeling a cooling system loop with pumps that pump water through, state-of-the-art chillers, filters that remove small particles, tubing, intercoolers, compressor cooling, and the precise geometry of everything involved. “Ansys was the tool with the breadth to cover this entire area with high precision,” says Finn Arcadi, Alaka’i’s engineering manager.
A contour plot for analyzing static pressure.
The team also used Ansys Discovery 3D product simulation software in their work. “Ansys Discovery simulation software is very easy to set up, easy to learn, and suitable for engineering problems,” says Karami. Using the Discovery software, designers can easily perform structural analysis, flow problems, and pressure drops early in the design phase, allowing more team members to access the power of simulation.
Looking back at the work done so far, “simulation saves so much time in developing a working product,” Arcadi says. It’s essential to be able to study a 1.8- to 2.2-ton vehicle in different scenarios with a low margin of error, and the Alaka’i team is relying on simulation to achieve that goal. In addition, the team emphasizes how simulation reduces costs by minimizing the number of prototypes and man-hours required for a test, making products like Skai more competitive.
A look into the future of urban air mobility
When the Alaka’i team envisions the future of Skai, they see an eVTOL aircraft that will bring a new level of freedom to individuals by providing an easy transportation option with an expected range of about 250 miles. In addition, the team is optimistic that the use of Skai will not only help reduce pollution and traffic congestion, but will also support essential workers in important applications such as disaster relief.
As next steps toward achieving these goals, the Alaka’i team hopes to expand simulation to analyze areas such as acoustics, to keep Skai’s noise levels low enough for populated areas, and aerodynamics, to further optimize the company’s design.
