Senior Mechanical Systems Engineer

Position Overview:

We are seeking a Senior Systems Engineer – Mechanical to own the detailed design validation, analysis, and ongoing optimization of Fleet’s data center cooling topology from campus level through the rack. This role requires a deep understanding of Fleet data center cooling topology, including air-side and liquid-side systems (fan walls, CRAHs/CRACs, chillers, dry coolers, pumps, heat exchangers, distribution manifolds, in-rack cooling components), and how these components interact under a variety of operating and failure scenarios.

The ideal candidate will pair strong mechanical engineering fundamentals with practical data center cooling experience, ensuring that the air-to-liquid mix and cooling configuration for each deployment match rack layouts and rack SKUs, that CFD and failure-mode simulations are routinely used to de-risk deployments, and that cooling system behavior is well understood and systematically improved. This role is accountable for end-to-end thermal system integrity, including aisle-level optimization, fan wall octet configuration, failure-mode simulations (e.g., CRAC outage, dry cooler outage), and impact assessment for infrastructure upgrades and expansions, with the goal of optimizing uptime SLAs and minimizing cooling stranding.

We have a hybrid policy, and candidates can sit in Seattle, WA, Denver, CO, Austin, TX, or Alexandria, VA

Responsibilities:

Cooling Topology Ownership & Rack-Level Alignment:

• Develop and maintain a deep understanding of Fleet data center cooling topology, including air-side systems such as fan walls, CRAHs/CRACs, air handlers, ducting, containment, and filters
• Develop and maintain a deep understanding of liquid-side systems including chillers, dry coolers, pumps, CDUs, heat exchangers, headers/manifolds, and valve trains
• Develop and maintain a deep understanding of rack-level solutions including liquid-cooled cold plates, rear-door heat exchangers, in-rack manifolds, and hybrid air/liquid configurations
• Determine the air-to-liquid mix needed to support a given rack layout and density, considering rack SKUs, aisle configuration, containment, and site constraints
• Ensure cooling topology and capacity at room and aisle level support current and forecast rack deployments and density targets

Rack SKUs, Cooling Requirements & Data Accuracy:

• Understand the air and liquid cooling requirements for each rack SKU, including inlet temperature and humidity ranges
• Understand liquid flow, pressure, and temperature ranges for cold plates and rear-door heat exchangers
• Maintain structured mapping from rack SKUs to required airflow per rack and aisle
• Maintain structured mapping from rack SKUs to required liquid flow per rack, manifold, and loop
• Maintain structured mapping from rack SKUs to special constraints such as mixed air and liquid aisles and maximum delta T
• Ensure specifications and counts for cooling components including fan wall modules, CRAHs/CRACs, CDUs, pumps, valves, manifolds, piping sizes, and coils are accurate, documented, and provided to capacity planning and procurement

CFD & Thermal Analysis:

• Perform CFD analysis at room and aisle level to validate that planned rack placement does not create hot spots
• Perform CFD analysis to confirm that airflow patterns, pressure profiles, and temperature distributions are within allowable limits
• Identify and mitigate cooling stranding where cooling capacity exists but cannot be effectively delivered to IT load because of placement or topology
• Use CFD and thermal modeling tools to evaluate different rack arrangements and containment strategies
• Use CFD and thermal modeling tools to test sensitivity to changes in IT load, fan speeds, supply temperatures, and air-to-liquid mix
• Quantify margin to thresholds such as maximum rack inlet temperature and maximum component temperatures
• Translate CFD results into actionable design rules, placement constraints, and deployment guidelines for capacity planners and operations

Aisle-Level Optimization & Fan Wall Configuration:

• Optimize cooling for each aisle based on actual and forecasted IT load distribution
• Optimize cooling based on air-to-liquid split for the racks in that aisle
• Optimize cooling based on containment strategy including cold aisle, hot aisle, full containment, and partial containment
• Recommend fan wall octet configurations and other fan wall module configurations per deployment
• Ensure configurations deliver required airflow and pressure with redundancy
• Maintain redundancy and margin for failure and maintenance scenarios
• Minimize energy use while maintaining thermal headroom
• Work with operations to tune setpoints including supply temperatures, fan speeds, differential pressure, and chilled water temperatures to support uptime SLAs and reduce cooling stranding and over-provisioning

Failure Mode Simulations & Uptime Optimization:

• Conduct failure mode simulations and analyses for mechanical systems including CRAC/CRAH outage scenarios, dry cooler outage scenarios, and pump or valve failures
• Evaluate transient and steady-state temperature excursions at the rack and component level
• Evaluate time-to-threshold for safe temperature limits
• Evaluate impact on redundancy, load shedding requirements, and achievable uptime
• Recommend design improvements such as additional redundancy, loop segmentation, and capacity rebalancing
• Define operational responses and MOPs including load shedding priorities and setpoint changes
• Optimize uptime SLAs while minimizing cooling stranding, especially in mixed air and liquid deployments and high-density aisles

Infrastructure Upgrades & Expansion Impact Analysis:

• Lead or support infrastructure upgrades and expansion impact analyses for cooling systems including adding or resizing fan walls, CRAHs/CRACs, dry coolers, chillers, pumps, CDUs, and distribution headers
• Support increasing liquid cooling fraction as AI-heavy racks grow in share
• Support changing setpoints or operating modes including supply temperatures and economization strategies
• Quantify effects on current and future thermal capacity and headroom
• Quantify changes in aisle-level and room-level airflow and liquid flow distribution
• Quantify impact on PUE, water usage, and operating costs
• Provide mechanical engineering input into MOPs and risk assessments for any cooling system change that could impact live IT load

Cross-Functional Collaboration & Documentation:

• Partner with capacity planners, rack design teams, site operations, facilities engineering, and procurement to ensure alignment between cooling design, deployment plans, and SLAs
• Ensure air-to-liquid decisions are integrated into forecast models and program timelines
• Produce and maintain design guides, reference one-lines, piping schematics, and airflow diagrams for baseline data halls and high-density deployments
• Contribute mechanical content to internal standards and playbooks covering cooling topology design rules, CFD methodologies, and failure simulation procedures

Required Qualifications:

• Bachelor’s degree in Mechanical Engineering or a closely related engineering discipline
• 6+ years of experience in data center mechanical engineering, mission-critical HVAC design, or thermal systems engineering
• Demonstrated deep understanding of data center cooling topologies including air-cooled and liquid-cooled architectures
• Hands-on experience performing and interpreting CFD analysis for data halls or similar environments
• Proven ability to determine air-to-liquid mix, optimize thermal performance, and identify hot spots and cooling stranding
• Experience analyzing failure modes for cooling systems and translating results into design improvements
• Strong analytical and problem-solving skills tied to uptime, SLA performance, and efficiency metrics
• Clear written and verbal communication skills

Preferred:

• Experience in hyperscale or colocation data centers supporting high-density AI/GPU clusters and liquid cooling
• Proficiency with CFD and thermal analysis tools and integration into DCIM or planning workflows
• Familiarity with PUE, WUE, and efficiency metrics
• Experience with DCIM, BMS, and monitoring systems
• Knowledge of mechanical and building codes for mission-critical facilities
• Experience with live data center upgrades and MOP development

Required Traits and Skills:

• Integrity and Ethical Standards: Make safety- and reliability-focused decisions in all cooling design and operations work
• Effective Communication: Clearly explain complex cooling and CFD concepts to technical and non-technical audiences
• Operational Paranoia: Anticipate risks and proactively prevent disruptions
• Strategic & Systems Thinking: Understand how local cooling decisions impact the full system and uptime SLA
• Critical Thinking & Analytical Ability: Use data, CFD, and testing to drive decisions and evaluate tradeoffs
• Collaboration & Relationship Management: Build strong partnerships across teams and vendors
• Leadership & Mentorship: Provide technical leadership and mentor junior engineers

Expected Salary Range: $120,000 - $150,000 Salary + Discretionary Bonus

Fleet Data Centers Employment

Fleet Data Center employees enjoy competitive compensation and comprehensive benefits, including 100% employer-covered medical, dental, and vision insurance, a 401K program, standard paid holidays, and unlimited PTO.