Impact of atmospheric boundary layer on large-scale BWEH performance: Empirical and numerical wake modification study

This study investigates the aerodynamic and structural performance of a large-scale Bladeless Wind Energy Harvester (BWEH) with and without a Thin Downstream Bluff Body (TDB) under both uniform and Atmospheric Boundary Layer (ABL) flows, simulating realistic environments. Using hot-wire anemometry and vibration response analysis, the impact of TDB on wake dynamics, turbulence, frequency behavior, and induced vibrations was examined. The addition of TDB increases the wake area by approximately 32%, while ABL flow reduces by 12% (without TDB) and 20% (with TDB). TDB reduced the average velocity drop by 11% and 23% under uniform and ABL flows, respectively. The average velocity in ABL was 30% lower than in uniform flow, emphasizing the influence of turbulence. TDB also stabilized turbulence intensity (TI), lowering the TI difference between ABL and uniform flow from 22% to 8%. Frequency analysis showed that TDB enriched the spectral content of the wake, improving flow-structure interaction, and also shifting the vortex shedding mods to P + S. Structurally, TDB increased vibration amplitudes by 85% in uniform flow and 74% in ABL, directly enhancing power generation. Despite induced vibration drops of 43% (with TDB) and 10% (without TDB) in ABL, TDB effectively mitigated losses. In a practical situation, by designing and manufacturing a mechanism to convert the vibration into power, it was shown that, in ABL flow, the generated power will drop by around 30%, and that applying TDB could increase the generated power by over 80%. Also, the coefficient of power decreases in ABL flow by about 30% compared to uniform flow. However, EFFA analysis revealed a 7–10% increase in required area for TDB-equipped BWEHs. Finally, the potential of wind energy harvesting using this technique is demonstrated, achieving peak efficiency gains of 74% to 85%, though its effectiveness is limited at U _r ≤ 7, and is discussed. Overall, TDB integration offers substantial benefits in energy harvesting under realistic wind conditions, making it a promising design solution despite spatial trade-offs.