**6. Conclusions**

In this study, a 2D Unsteady RANS Transition SST model was used to study the performance of a small-scale H-type Vertical Axis Wind Turbine with an NACA 0018 airfoil. A spatially randomised inlet velocity was generated to produce a macro-turbulent domain upstream of the turbine. The study focused on understanding the effect of the magnitude of randomness and the frequency of change in randomness in upstream wind on the coefficient of power (Cp) and the coefficient of moment (Cm).


tip speed ratios. Wake recovery was faster in the case of lower tip speed ratios. Wake generated by uniform velocity inlet had slower wake recovery compared to randomised velocity inlet. Macro-turbulence generated by randomisation enhanced the mixing of flow downwind of the turbine, allowing faster recovery.


**Author Contributions:** Conceptualization, R.K.V. and U.D.; methodology, L.S. and N.R.; software, R.K.V. and A.M.; formal analysis, L.S., N.R., U.D. and S.B.R.; resources, R.K.V. and A.M.; writing—original draft preparation, L.S., N.R. and S.B.R.; writing—review and editing, R.K.V., A.M. and U.D.; supervision, R.K.V. and U.D. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** A part of the computations were performed on the Aziz Supercomputer at King Abdulaziz University's High-Performance Computing Center (http://hpc.kau.edu.sa/). The authors acknowledge the computer time and technical support provided by the center.

**Conflicts of Interest:** The Authors declare no conflict of interest.
