Mechanism and Position-Dependence of Inter-Unit Aerodynamic Coupling in Parallel Blower Systems

Abstract When several blowers discharge into a shared manifold they operate against a common pressure rise and are coupled aerodynamically, yet the mechanism and position-dependence of this coupling have rarely been characterized experimentally. Unlike the inflow coupling of distributed propulsor arrays or the near-surge interaction of parallel compressors, the coupling in a blower manifold operating far from surge is transmitted pneumatically through the gas volume of the shared discharge manifold. This work characterizes it in an operating four-blower manifold from synchronized measurements of manifold pressure, blower flow and power, across different configurations. A multiple-input single-output regression identifies the steady-state coupling and reveals a non-monotonic dependence on position: adjacent blowers couple most weakly in the power domain, while a pressure-domain analysis recovers its true strength. A directional transient analysis confirms this mechanism: the target blower’s flow responds sign-coherently to a neighbor’s setpoint step, decreasing for an upward step and increasing for a downward one. Spectral and statistical analysis places the system in a quasi-static regime. The coupling is thus real, directional, and mechanistically identifiable, establishing pneumatic head-loading as the governing inter-unit interaction in shared-manifold blower systems.