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1

Study of flow pattern on a hydrofoil with structural and profile modification

Chada Jithendra Sai Raja, Rao B. S. V. Rama

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 1

27--31

EN

Moving through water takes much more effort than walking through air, and this explains why ships travel much more slowly than automobiles and aircraft. Water is almost 1000 times denser than air, so most of the energy produced by a boat is taken up by dragging (water resistance). Hydrofoils travel much more quickly than ordinary boats, not by pushing through water but by raising the hull (the main body) of the boat upward so it can glide above the waves. Hydrofoil is one of the typical factors that affect the vortex structure and flow characteristics of hydraulic machinery. In order to enhance the utilisation efficiency of hydraulic machinery in marine energy, parallel grooves are proposed and applied to the hydrofoil. Following that, a numerical analysis is performed using the SST k- turbulence model, and the effects of the hydrofoil profile, the angle of attack and the flow are investigated. The profiles of NACA 0066, NACA 8412, NACA M2 and RAE 104 are considered for the study. The performance is analysed based on the lift to drag ratio. The best model from this is given with surface modification and the flow study is carried out at different angles of attack. The modified profile of NACA 8412 with parallel groves has shown the highest lift to drag ratio at a 12 degree angle of attack.

2

The experimental studies on hydrofoil resistance

Reichel M., Bednarek A.

Archives of Civil and Mechanical Engineering

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2007

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Vol. 7, no 3

167-175

EN

This paper presents the hydrofoil resistance model tests which were performed at Ship Design and Research Centre (CTO S.A.). The measurements were carried out in the large towing tank of Ship Hydromechanics Division. A four meters long wooden hydrofoil model was tested. The model was equipped with two lifting foils and a stabilizing front foil. The measurements were conducted for a combination of three values of static trim and two foil angles of attack. A new methodology of shaft angle optimisation with vertical force simulation is presented. The simulation system is an integral extension of the standard dynamometric system for resistance measurements. This paper presents some aspects of the test methodology. The results are briefly presented in the form of standard non-dimensional coefficients in the function of volume Froude number.

PL

Artykuł przedstawia badania modelowe oporu wodolotów przeprowadzone w Centrum Techniki Okrętowej S.A. Badania zostały przeprowadzone na dużym basenie holowniczym Ośrodka Hydromechaniki Okrętu. Eksperymentowi poddany został czterometrowy, wykonany z drewna, model wodolotu, wyposażony w dwa płaty nośne oraz stabilizujący płat dziobowy. Pomiary oporu przeprowadzone zostały dla kombinacji trzech wstępnych kątów przegłębienia i dwóch kątów natarcia płatów nośnych. Artykuł zasadniczo przedstawia badania modelowe w aspekcie metodologicznym. Przedstawiono nowo wdrożoną metodykę badań, umożliwiającą optymalizację kąta nachylenia linii wałów napędowych, związaną z symulacją składowej pionowej siły naporu. Krótko, przedstawiono także wyniki pomiarów w postaci standardowych, bezwymiarowych współczynników oporu w funkcji liczby Froude'a.

3

Hydrofoil craft motions in rough sea

Krężelewski M.

Systems : journal of transdisciplinary systems science

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2006

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Vol. 11, nr 1

35-43

EN

At present, we have well-elaborated theory and practical methods for predictions and investigations of hydrofoil craft longitudinal motions in regular waves and in wind waves. Whereas in the field of lateral motions, works are concerned in pure rolling or stabilization for deeply submerged foils. Therefore, in the paper, the more general linear mathematical model and practical method for investigation of lateral motions characteristics of hydrofoil craft are outlined. The new model of craft motions comprises coupled swaying, yawing and rolling when hydrofoil craft is flying, at any courses relative to main direction of wave's propagation in a fully developed rough sea. Using the method, many investigations are performed and some results are presented.