reza dorostkar

Traditional dhow has been used for years in Iran and other countries in the Persian Gulf and Oman Sea for the transportation of goods and fishing. Today, these vessels are still operational in Iran and play an important role economically. The construction of these vessels is always done traditionally and no scientific research has been done on its design. In the present study, the hydrodynamic resistance, and motions of a dhow model in the towing tank have been investigated experimentally. A model with 95 cm long was made from a real dhow with a length of 21.1 meters and tested in the NIMALA towing tank. Also, the resistance of the dhow model has been calculated using the Holtrop method. The results show that with the increase in speed, the trim of the model increases and reaches 6.8 degrees at a speed of 1.5 m/s. Also, increasing the speed increases the sinkage of the model and at high speeds, the sinkage increases by 2 cm. At the design speed (1.1 m/s), the resistance of the dhow model is 2.476 N, and when the speed increases to 1.5 m/s, the resistance increases sharply and reaches 15.62 N. Also, the results show that the Holtrop method has an acceptable accuracy compared to the experimental results, and this method can be used, in addition to commercial ships, to estimate the resistance of vessels with special bodies such as dhows.

The use of offshore wind turbines has attracted the attention of researchers recently. For enhancing the performance of power generation, the combination of these platforms with wave energy converters has been investigated. The integrated design of an oscillating surge WEC with a semi-submersible offshore platform has less been considered. Moreover, the effect of flap dimensions and wave direction on the dynamic response in roll, pitch, heave surge direction, and output power has not been studied which is investigated in the present study. The results confirmed the effectiveness of the hybrid system on vibration reduction and power production compared to the alone platform. The flap width is more effective than height and thickness on power production and platform response. The output power of 1000 kw can be generated depending on the flap dimension of the wave period. Furthermore, the dynamic response decreases up to 30% in hybrid design indicating the higher stability of the platform when attaching to WECs.

Traditional barges have been used for years in Iran and other countries in the Persian Gulf and the Oman Sea for transporting goods and fishing, and they play an important role economically in the lives of the people of the south of the country. The construction of these vessels is done traditionally and so far no complete research has been done on the added resistance and movements of these floats.In the current research, the experimental investigation of the added resistance of the dhow vessel in waves has been investigated. A 95 cm long barge model was made from a vessel with a length of 21.1 meters and tested in the Persian Gulf Martyrs towing tank. Tests have been done in calm water and regular waves at different speeds. The results of the tests show that the dynamic trim at low speeds is a small amount due to the lower pressure in the floating chest. With the increase in speed, the dynamic trim increases due to the increase in pressure in the bow of the vessel. The results of the added resistance floating in the waves show that at low speeds, the added resistance is very high, but as the speed increases, the added resistance decreases, and even at very high speeds, the added resistance becomes negative.

Increasing the performance of offshore platforms is one of the main aims of the designers. The oil and gas offshore platforms encounter some challenges as the dynamic vibrational response that they always attempt to improve the stability and response of the platforms. On the other hand, many electronic devices on the platform require a supply resource. The transmitted energy of the excited waves into the mechanical vibrations for the platform may be captured by installing some types of WECs. The present study conducts a numerical study on the hydrodynamic analysis of the platform attached with four-point absorber wave energy converters underneath the Amir Kabir semi-submersible platform. The monochromatic regular waves are considered the excitation forces based on the Caspian Sea state. Two different arrangements of WECs and three sizes of sphere buoy are also considered. In addition to calculating the produced power via WECs, the overall performance of the single and integrated platforms is compared from the dynamic response point of view. The results show a considerable difference in the responses of the platform when the WECs are combined. However, the captured power does not depend on the locations of the WECs but is affected by the buoy size of the WECs while the platform response is dependent on the buoy size and also the WECs’ arrangement.