Principal Thermal Mechanical Engineer

Job Summary Principal Thermal Mechanical Engineer located in Littleton, MA. Reporting to the Mechanical Development Associate Principal Engineer, the role plays a pivotal part in the early stages of product development and guides the product through maturation. The focus is on designing and engineering fluid and thermal systems that enable higher coolant temperatures and improved heat capture for liquid cooling across data center infrastructure. Responsibilities Lead the architecture, design, analysis, and optimization of complex fluid and thermal systems—including pumps, fluids, tubing, heat exchangers, and associated components—for advanced computing and processing platforms. Own mechanical and fluid system deliverables from concept through production, ensuring that designs meet performance, reliability, manufacturability, and compliance requirements. Serve as a technical partner to customers and external collaborators, supporting system‑level integration of fluid solutions into broader product architectures. Drive simulation, analysis, and test efforts to validate fluid flow, pressure drop, thermal performance, and material compatibility across operating conditions. Develop, review, and approve engineering requirements, specifications, and technical documentation in accordance with applicable industry standards and regulatory expectations. Lead and influence design reviews, presenting technical tradeoffs, risks, and recommendations to cross‑functional teams, customers, and senior stakeholders. Identify technical gaps and emerging challenges, advocate for targeted research and development, and lead exploratory efforts that build foundational knowledge and intellectual property. Establish and promote best practices in fluid system design, analysis, and documentation, contributing to a strong engineering culture and continuous improvement. Provide technical leadership, mentorship, and guidance to engineers across experience levels, supporting professional development and raising overall team capability. Contribute to new product innovation by evaluating emerging technologies, industry trends, and alternative architectures to drive differentiated fluid system solutions. Support the resolution of complex technical issues throughout the product lifecycle, including development, qualification, production, and field support as needed. Qualifications Minimum of 7+ years of experience designing and engineering fluid systems in data center thermal management and cooling, automotive, medical, or nuclear industries, including at least 3+ years of direct experience with Coolant Distribution Units (CDUs). Deep expertise in fluid dynamics, thermodynamics, and heat transfer, with strong application of first‑principles engineering. Proven track record of new product development in thermal or fluid systems, including concept development, performance analysis, validation testing, and experimental design. Strong analytical and problem‑solving capabilities, with demonstrated ability to troubleshoot and optimize complex fluid systems across development and production phases. Demonstrated technical leadership within a structured product development environment, with clear ownership of mechanical design deliverables from concept through release. Experience leading and mentoring development teams, driving technical direction, coordinating cross‑functional efforts, and ensuring alignment to product requirements and schedules. Accountability for product‑level mechanical execution, including leading design reviews, resolving technical risks, and ensuring designs meet performance, reliability, manufacturability, and compliance requirements. Strong communication and technical documentation skills, with the ability to clearly communicate complex concepts to technical teams and senior stakeholders. Benefits Full range of medical, dental, and vision plans Life Insurance Short‑term and Long‑term Disability 401(k) Matching contributions Vacation and Paid Sick Time Tuition Reimbursement Pay Range (Applicable to Massachusetts) $153,500.00 USD – $211,000.00 USD annual. EEO Statement JetCool is an Equal Opportunity Employer and employment selection decisions are based on merit, qualifications, and abilities. We do not discriminate based on age, race, religion, color, sex, national origin, marital status, sexual orientation, gender identity, veteran status, disability, pregnancy status, or any other status protected by law. We are happy to provide reasonable accommodations to those with a disability for assistance in the application process. Please email View email address on click.appcast.io and we will discuss your specific situation and next steps. (NOTE: this email does not accept or consider resumes or applications. This is only for disability assistance.) #J-18808-Ljbffr Flextronics - The Flex Company