Nikola Vranjic

12 years of experience solving mission-critical heat transfer and fluid dynamics challenges across aerospace, gas turbines, eVTOL, high-performance EVs, and energy systems.

I work on thermal systems where failure carries system-level consequences: high power density hardware operating close to physical and operational limits, where small design errors cascade.

I operate as an independent thermal engineering contractor through my own company, supporting clients on a B2B basis.

My experience spans both electrified and combustion-based high-energy systems. At Rimac Automobili, I led the thermal team delivering solutions for battery systems and power electronics for OEM programs. In eVTOL, I owned thermal system performance at Lilium. I am also the lead inventor of patented gas turbine cooling technology (GE).

In parallel, a 7+ year technical advisory engagement with X-therma has shaped my approach to product development and validation in phase-change thermal systems.

My methods combine CFD/CHT, 1D system modeling, and test correlation to:

• define robust thermal architectures before metal is cut
• identify risks early in development
• close the gap between simulation and real hardware behavior

I am typically engaged when thermal performance is uncertain, simulation and test results diverge, or systems are pushed beyond conventional design limits.

Experience eVTOL Propulsion and Aerothermal Integration, Lilium, 2021 to 2024

• Defined thermal strategy for propulsion systems under weight and integration constraints
• Performed 1D and 3D trade offs for cooling concepts
• Delivered 3 Technical Design Specifications supporting hardware validation and certification

High Performance EV Powertrain Development, Rimac Automobili, 2018 to 2021

• Led thermal development for battery systems, power electronics, and vehicle applications
• Managed thermal team of 10 engineers
• Delivered solutions for OEM programs, Porsche, Hyundai, Koenigsegg

Gas Turbine Cooling Development, General Electric, 2014 to 2018

• Developed cooling concepts for combustor components under extreme loads
• Designed additive manufactured burner components
• Lead inventor on patented solution improving efficiency and reducing cost and emissions

Technical Toolbox

• CFD and CHT: StarCCM, ANSYS Fluent, OpenFOAM, CFX, ICEM, Fluent Meshing
• 1D Systems: MATLAB Simscape, Flowmaster, OpenModelica, Dymola
• Thermal and structural: ANSYS Workbench, SC03
• CAD and PLM: CATIA v5, Solidworks, SpaceClaim

Master of Mechanical Engineering in Energy Engineering - Turbomachinery – University of Zagreb (2015)