Principal​/Thermal Mechanical R&D Engineer

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USA, MA, Littletontime type:
Full time posted on:
Posted Todaytime left to apply:
End Date:
February 27, 2026 (27 days left to apply) job requisition :
WD210948

Job Posting Start Date 01-30-2026 Job Posting End Date 02-27-2026

At Jet Cool, a Flex company, we’re at the forefront of liquid cooling innovation, delivering advanced solutions that empower our partners in AI and high-performance computing. United by a shared purpose, our teams are pushing the limits of what’s possible and tackling complex challenges.

A career at Jet Cool offers the opportunity to make a real impact by helping build smarter, more sustainable data centers. Together, we’re not just advancing technology — we’re redefining cooling standards to create a more sustainable tomorrow.##

Job Summary To support our exceptional teams in building innovative products, we are seeking a
** Principal
* *** Thermal/Mechanical R&D Engineer
** based in
** Littleton, MA**. Reporting to the
** Sr. Director of Research & Development**, the
** Principle*
* ** Thermal/Mechanical R&D Engineer
** role is responsible for creating and implementing advanced, cost-effective thermal and mechanical designs that deliver outstanding product performance from early development through full-scale production. The Principal Engineer will provide technical leadership and mentorship while applying deep expertise in mechanical design, fluid dynamics, and heat transfer. In addition, this position will work closely with customers to deliver Jet Cool’s cutting-edge cooling solutions and foster strong technical relationships.
** What a typical day looks like:
*** Drive innovation by introducing new ideas and critical thinking to advance cooling technologies for improved performance, manufacturability, and reliability.
* Lead the conceptual design, analysis, and optimization of complex fluid systems, including pumps, fluids, tubing, and heat exchangers, for next-generation processors.
* Perform advanced fluid flow simulations, analyses, and validation tests to ensure optimal performance under various operating conditions while collaborating with customer and cross-functional teams to integrate fluid systems into overall product designs.
* Develop and review engineering specifications, and documentation for fluid system and heat transfer components and assemblies, ensuring compliance with industry standards and regulatory requirements.
* Oversee prototype fabrication, testing, and validation, diagnosing and resolving technical issues during development phases and provide technical guidance and mentorship to junior engineers.
* Assist in maintaining a strong best practice culture and driving additional foundational knowledge and IP through research.
* Identify technical gaps, advocate for R&D initiatives, IP, and lead research projects to maximize product impact and value.
** The experience we’re looking to add to our team:
*** Master's (Thesis required) degree in Mechanical Engineering or related field.
* Minimum of 7 years of post-collegiate experience in designing and engineering thermal fluid systems, preferably within the data center cooling, automotive, combustion, aerospace, medical, or nuclear industries.
* Profound expertise in fluid dynamics, thermodynamics, and heat transfer, with a strong foundation in engineering principles.
* Strong…