Time-resolved exergy analysis and operating parameters optimization of pulse detonation combustor

The exergy of exhaust gases from pulse detonation combustor (PDC) is critical for pulse detonation engine performance. However, conventional cycle-averaged exergy analysis fails to capture the unsteady exhaust characteristics of PDC. To address this gap, this paper proposes a novel time-resolved exergy analysis method dynamically tracking transient flow unsteadiness, variable specific heat, and variable gas composition during exhaust process. Time-resolved and cumulative exhaust exergy were calculated using flow parameters from a zero-dimensional analytical PDC model. Exergy efficiency and equivalent specific exhaust exergy (ESEX) were employed as core performance metrics to investigate the effects of compressor pressure ratio (CPR), equivalence ratio (ϕ), and operating frequency (f). To validate the necessity of the proposed method, a systematic comparison with conventional cycle-averaged analysis was conducted. Furthermore, Response Surface Methodology (RSM) was employed for parameter influence analysis and optimization. The results indicated that: increased CPR reduced both metrics primarily due to elevated PDC inlet temperature; exergy efficiency peaked at ϕ = 0.8, while ESEX peaked at ϕ = 1.1; and increased operating frequency caused a linear decline in both metrics. In comparison, conventional cycle-averaged methods underestimated exergy efficiency and ESEX by approximately 10–20%. Notably, RSM identified ϕ as the most significant factor affecting performance metrics. Based on the RSM model, the optimal operating parameters were determined as CPR = 3, ϕ = 1.0, and f = 10 Hz, yielding a maximum exergy efficiency of 65.60% and ESEX of 2080.54 kJ/kg. These findings not only provide significant theoretical guidance for unsteady combustion gas exergy assessment, but also enable more accurate economic and environmental evaluations by eliminating the bias introduced by conventional methods.