07/23/2026 updated

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Lead Thermal Systems and CFD Engineer | Leitender Ingenieur Thermik und CFD

Zagreb, Croatia
Worldwide
Master of Mechanical Engineering | M.Eng. Maschinenbau
Zagreb, Croatia
Worldwide
Master of Mechanical Engineering | M.Eng. Maschinenbau

Profile attachments

Nikola Vranjic- Senior Thermal Systems Expert - One Pager.pdf
Nikola Vranjic - Lead Thermal and CFD Engineer Apr2026.pdf

About me

Fixing thermal challenges in high-power energy & flight systems (SMR, gas turbines, EV, eVTOL, aerospace) | Thermal Systems Engineer (CFD & V&V) | Ex-GE, Rimac, Lilium | High Power Density Cooling | Open to Contract

3D PrintingThermodynamicsComputational Fluid DynamicsFluid MechanicsHeat TransferMATLABThermal AnalysisAnsys

Principal Thermal Systems Engineer
Aerospace • Electromobility • Power Generation • High power density cooling

Executive Summary
Thermal Systems Engineer with 11+ years of experience delivering cooling solutions for Lilium, Rimac, and GE / Alstom. Focus on system level thermal concepts and execution through simulation, validation, and hardware. Track record in reducing thermal risk and supporting testing and certification.

Core competencies
• System level strategy: requirements, cooling concepts, trade off studies for propulsion and high power density systems
• CFD and CHT: 3D CFD, conjugate heat transfer, multiphase, StarCCM, ANSYS Fluent, CFX
• Multi fidelity coupling: 1D and 3D models, MATLAB Simscape, OpenModelica, transient missions
• Additive cooling design: patented cooling geometries for gas turbine applications
• Testing and validation: correlation with bench and system test data
• High power density cooling: gas turbine components, battery systems, electronics

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

Skills and tools
• 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
• Languages: English full professional, German A1 A2 (improving)

Consultancy Model DACH Region
• Availability, 100 percent
• Setup: onsite, hybrid, remote
• Location, Greater Munich Area, based in Zagreb

Experience

Professional experience10+ years
Freelancer since2019

Languages

GermanBasic knowledgeEnglishFluentItalianBasic knowledgeCroatianNative speaker

Project history

Lead Thermal Systems Engineer

thermIT consulting
Providing expertise in thermal analysis and thermal management in aerospace, EV automotive, energy, biomedical and biotech. Cooling system design, thermal energy storage design, human organ cryo-preservation solutions, thermal analysis including CFD, CHT, 1D, latent heat, hand calculations. Notable clients include Aerospace Lilium and Biotech X-therma.

Thermal System Engineer (contract)

Lilium
Thermal strategy and approach setting, thermal requirements capturing and validation support, propulsion system cooling development and aerothermal integration of propulsion electric motor and propulsion vectoring systems. PVS thermal management achieved with air cooling and without additional active components resulting in weight reduction and increased reliability. Conceptual studies and trade-offs for electric engine cooling concept, technical go-to person for propulsion vectoring system thermals.

Thermal Team Lead

Rimac Automobili
Increased the team from 2 to 10 people. Lead 1D and CFD activities including method development and validation. Introduced advanced CFD modelling for powertrain and battery thermal management, multi-phase flows in filling and air entrapment issues. Organizing and distributing work according to Agile methodology, reviewing work from colleagues spread across multiple projects. People development, business continuity and process development. Coordinated and managed expectations from internal and external stakeholders including Rimac Nevera, Porsche, Ferrari, AMG, ARB, Hyundai, Koenigsegg.

CFD Engineer

Rimac Automobili
Aerodynamic and thermal modelling including CFD, Conjugate Heat Transfer, 1D, spreadsheets. Cooling concept design, feasibility studies for internal and external customers. Electric powertrain cooling and lubrication, EV Battery and power electronics cooling. Supporting the development of Rimac C_Two, Porsche, Hyundai, and other established OEMs in electrifying their vehicles.

Gas Turbine Combustor Cooling Engineer

General Electric (legacy Alstom)
Hot path component cooling design with key achievement as lead inventor of patented 3D printed burner front plate, resulted in increase in efficiency, decrease in manufacturing cost and pollution. Aerodynamic and thermal modelling using CFD, FEM, 1D. Additive manufacturing design for combustor and turbine components. Test definition and test rig data evaluation. Supported 9HA.02, 7FA.05, GT36, GT26, GT13 inlet, combustor cooling, turbine cooling, diffuser aerodynamics and thermal stress analysis. Export control tagger, worked as part of international teams.

Portfolio


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