Test Engineer, Thermofluids

ABOUT FLUIDSTACK

We exist to make humanity more free. For most of human history, you farmed or you starved. Technology gave people more time for the things they wanted to do, instead of things they had to do. Powerful AI will be the biggest lever for human choice we've ever built - but only if models are aligned with what humanity actually wants. There are groups building AI who don't share these goals. Whoever deploys frontier compute infrastructure fastest will decide whether AI expands human freedom or shrinks it.

We're singularly focused on delivering 10 to 100s of GWs of compute faster than anyone else, rethinking every layer of the stack. We acquire power, design and build data centers, and operate them - with teams spanning hardware and software. Speed and scale are our key differentiators. Come be a part of building civilization-scale infrastructure for AI.

We hire people who care deeply about this problem space. If that is you, please apply!

HOW WE OPERATE

- Be a barrel. Full autonomy. Own things end to end, take on scope without being asked, no permission required to operate outside your core role.

- Insane urgency. We drive everything forward as fast as possible.

- Reason from first principles. Challenge every assumption. Zero analogy thinking, no egos, the best idea wins.

- Love of the game. The frontier of AI is the most interesting problem of our time. We put in long hours at high intensity to push the frontier forward.

- Build something that actually matters. If you're going to spend your time, spend it on something that matters to the world.

THE THERMOFLUIDS R&D TEAM

Examples of key problems the team is working on

- Reject 10s of GW of heat, starting now. Fluidstack is targeting 10s of GW of compute over the next two years. Every watt of it becomes heat that has to go somewhere, and no cooling team has ever been asked to open at that scale rather than grow into it.

- Design and build the machines, because nobody can supply them. The merchant compressor market cannot deliver at this rate, and the vendor base behind today’s chillers will not scale to gigawatts. We are taking compressor and chiller design in house, working on machine architectures nobody sells today, and going from blank sheet to production faster than this industry thinks is possible.

- Own every thermofluids problem behind the fleet, not just the chiller. Working fluid and cycle architecture, heat exchangers at a scale that dominates the cost of the plant, two-phase heat transfer at the chip, and thermal energy storage. All of it is open, and whatever this team lands gets built thousands of times.

ROLE SCOPE

- Own the test program that takes the compressor from first spin on the stand to a validated performance map the design team can build on.

- Specify and stand up the test cells from an empty bay: motor test bench, high-pressure gas loop, load bank, and every instrument behind them.

- Define the measurement chain and the uncertainty budget, so a claimed isentropic efficiency or COP survives scrutiny from outside this company.

- Write the test plans, interlocks and abort criteria for a machine running at speeds and pressures where a failure is energetic.

- Turn test data into design changes on a weekly cadence, sitting inside the design loop rather than reporting into it.

WHAT WE'RE LOOKING FOR

The below is a starting point. We always make space for exceptional people, so if you don't fit this role exactly, tell us where you would https://jobs.ashbyhq.com/fluidstack/05c2e69c-42f9-4fcb-9cf0-a467aaf98f1c.

- 10+ years of experience in test engineering for rotating machinery or high-energy mechanical systems, including test stand design, instrumentation, and data analysis.

- You’ve commissioned a test stand from a bare bay: instrumentation, calibration, shakedown, first article.

- You’ve taken a machine to failure deliberately and had it instrumented well enough to know exactly why it failed.

- You’ve owned an uncertainty budget and could tell someone what your measurement was actually worth.

- You’ve written interlock and abort logic that kept people safe around stored energy, high pressure or high speed.

- You’ve disagreed with a design team about what the data showed, and the data won.

- You’ve carried a failure investigation to a root cause that changed the hardware, rather than to a plausible story that closed the paperwork.

- Bonus: Propulsion and engine test (hot fire, spin pit, green run). Rotating machinery test (compressors, turbines, motor test benches). High-pressure gas loops and pressure-rated test rigs. Data acquisition and rig control (LabVIEW, NI, PLC-based stands). Thermal and refrigeration performance testing (COP mapping, calorimetry).

We are committed to pay equity and transparency.

Fluidstack is an Equal Employment Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, sexual orientation, gender identity, disability and protected veterans’ status, or any other characteristic protected by law. Fluidstack will consider for employment qualified applicants with arrest and conviction records pursuant to applicable law.

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You will receive a confirmation email once your application has successfully been accepted. If there is an error with your submission and you did not receive a confirmation email, please email careers@fluidstack.io with your resume/CV, the role you've applied for, and the date you submitted your application-- someone from our recruiting team will be in touch.