Flap-type wave energy converters (OWSCs) are used near the coast to generate electricity and pump water. The draft depth and incident wave frequency are parameters affecting the performance of this type of converter. In this paper, the effect of water draft depth and incident wave frequency on the performance of a converter at a scale of 1: 8 has been investigated experimentally. The power take-off system (PTO) is hydraulic. The Caspian Sea was also selected as the target sea. After calibration of equipment and uncertainty analysis, experimental tests were performed in the wave flume of Babol Noshirvani University of Technology by considering regular waves. Considering the predominant period of the waves of the Caspian Sea ([4-8] seconds), after Froud scaling, the tests were performed in the period interval of [1.6-2.5] seconds, which is equivalent to the frequency interval [0.4-0.63 ] Hz. Also, due to the importance of the converter's draft depth, the converter's performance was evaluated from the draft depth of -0.1 (submerged flap) to 0.6 m. According to the results, the best converter performance was at the lowest frequency; the converter performance decreased with increasing frequency. The best converter performance was obtained at the dimensionless draft depth of 0.43 (equivalent to 0.4 m draft depth), and the converter power was reduced at larger and smaller draft depths. It is worth noting that at a negative draft depth (submerged flap), the converter has the lowest performance. The maximum values of flow, power, and pressure on a laboratory scale were 0.14 liters per second, 21.3 watts, and 156.8 kPa, respectively, which were measured at 18 liters per second, 22.66 kW, respectively, using Froud scaling method and will be 1249/61 kPa.

The effect of installation depth and height of the incident wave on the hydrodynamic and economic performance of an oscillating wave surge converter (OWSC) wave energy converter is crucial. In this study, an OWSC by considering 1:8 scale has been studied under Caspian Sea wave conditions for 8 water depths from the semi-submerged to fully submerged. The study has been conducted to achieve the best draft ratio and evaluate the systems performance imposed to Caspian waves condition by experimantal method.The results are presented in three parts. The first part studied the converter's flow, power, and sensitivity to the installation depth on a laboratory scale. In the second part, the system results were converted to the main scale 1:8 by using Froude scaling method, and finally, the performance from an economic view evaluated. Results showed that the draft depth has a non-linear effect on the power. System's power in the dimensionless draft depth of 0.59 is better, and can produce 61 kW. Also, it can pump up to 50 l/s of water. Likewise, suppose the system is used for electricity generation, In that case, it sells $22500 of electricity to the grid annually, and if it is used as a pump, it can supply water to 4710 households on average.