Sr. Systems Engineer – Mechanical

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

Develop and maintain a deep understanding of Fleet data center cooling topology, including:

Air‑side systems: fan walls, CRAHs/CRACs, air handlers, ducting, containment, filters. Liquid‑side systems: chillers, dry coolers, pumps, CDUs, heat exchangers, headers/manifolds, valve trains. Rack‑level solutions: liquid‑cooled cold plates, rear‑door heat exchangers, in‑rack manifolds, hybrid air/liquid configurations. Determine the air‑to‑liquid mix needed to support a given rack layout, accounting for:

Rack SKUs and thermal design power per rack/cluster. Liquid‑cooled vs. air‑cooled SKUs and their specific inlet temperature, flow, and ΔT requirements. Aisle‑level and room‑level constraints (supply/return temperatures, pressure, containment). Ensure that for each deployment:
The selected cooling topology supports the planned rack densities and layouts. Air and liquid paths are balanced to avoid local under‑supply or over‑supply conditions. Design assumptions are documented and traceable back to rack SKUs and IT deployment plans. Rack SKUs, Cooling Requirements & Data Accuracy

Understand the air and liquid cooling requirements for each rack SKU, including:

Inlet temperature and humidity ranges. Liquid flow, pressure, and temperature ranges for cold plates and rear‑door heat exchangers. Allowable gradients across the rack and between front/rear or supply/return. Maintain a structured mapping between rack SKUs and required cooling configuration, including:

Airflow requirements per rack and per aisle. Liquid flow per rack, per manifold, and per loop. Any special constraints (e.g., high ΔT, mixed air/liquid in same aisle, hot aisle / cold aisle rules). Ensure all cooling‑related specifications and quantities (fan wall modules, CRAHs/CRACs, CDUs, pumps, valves, manifolds, piping sizes, coil sizes) are:
Accurate and complete. Captured in standardized BOMs and drawings. Provided to capacity planners and procurement with enough detail to plan and procure infrastructure. CFD & Thermal Analysis

Perform CFD analysis at room and aisle level to:
Validate that planned rack placement does not create hot spots. 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. Test sensitivity to changes in IT load, fan speeds, supply temperatures, and air‑to‑liquid mix. Quantify margin to thresholds (e.g., maximum rack inlet…