Pulse detonation combustors (PDCs) allow for reliable and robust pressure gain combustion. However, the combustion process including flame acceleration, deflagration-to-detonation transition, and propagation of a detonation generates high pressure peaks that propagate inside the combustor. When integrating a PDC into a gas turbine, low pressure loss at the inlet of the combustor is desirable to allow for high cycle efficiency. However, in a valveless design pressure waves with high amplitudes can travel upstream into the air supply. These pressure pulses may block the desired continuous air flow, and thus, impeding a fast purging of the combustor. In addition, these pressure waves may harm the operation and the durability of the compressor when integrating the PDC into a gas turbine.

A valveless PDC-multitube test rig with six annular distributed combustion tubes and an annular plenum downstream  of the combustors  is set up. In this work, the pressure fluctuations inside the air supply of the test rig are investigated. First, appropriate measurement methods are identified. The obtained data are then interpreted accounting for the combustion events inside the PDC tubes. Finally, operating parameters (equivalence ratio, fill fraction, and firing frequency) and firing patterns (simultaneous, sequential, and hybrid patterns) are varied to assess their impact on the detected pressure fluctuations.