276 



HYDRODYNAMICS IN SHIP DESIGN 



Sec. 54.3 



2.1 2.0 1.9 1,8 I.T 1.6 1.5 1.4 1.3 1.2 I.I 1.0 

 Rotio of Wind Velocit'^ Wj^ at h ft to Velocitvj Wq ot G ft 



Fig. 54.A Graphs Indicating Variation of Wind 

 Velocity with Height 



Fig. 2 of this reference is a set of graphs of wind 

 velocity with height, carried up to 43 meters per sec 

 velocity and 60 meters height. The paper contains a 

 set of rather complete wind-resistance calculations 

 for the Atlantic liners Mauretania (old) and Kaiserin 

 Auguste Viktoria. 



(b) White, Margaret, "On the Velocity and Direction of 



the Wind Above Ground Level," Brit. Assn. Rep., 

 1912, pp. 420-422 



(c) U. S. Chemical Warfare Service data, Edgewood 



Arsenal, Md., 1934, applying to variation of wind 

 velocity with height over "open, unobstructed 

 ground" 



(d) Fox, Uffa, "Sail and Power," New York, 1937, p. 196 



(e) Hanovich, I. G., Soloviev, U. I., and Churmack, 



D. A., "Korabelnie Dvizhitelni (Marine Propulsion 

 Devices)," Moscow, 1949, BuShips Transl. 408, 

 Mar 1951, p. 332 



(f) Yachting, Jul 1950, p. 34, giving data taken at sea by 



a German oceanographic expedition, 1936 



(g) "Trial Results of Hakubasan Maru," Experiment Tank 



Committee, Japan, 1951, embodied in "Abstract 

 Notes and Data," 6th ICSTS, pp. 71-92 

 (h) Koppen, Ringbuch der Luftfahrt, IDI; reprinted by 

 Henschke, W., in "Schiffbautechnisches Handbuch 

 (Shipbuilding and Ship Design Handbook)," 

 Berlin, 1952, Fig. 17, p. 120. The mean curve given 



here, derived from experimental data, lies very 

 close to the short-dash line B curve of Fig. 54.A, 

 representing the fifth-power law. 



Wind velocities W measured by an anemometer 

 placed well above the hull might — and probably 

 do — exceed those causing the actual Avind resist- 

 ance on a ship. Certainly an anemometer at deck 

 level on a sailing yacht, whether a mechanical 

 instrument or the nerves of the human face, is 

 not a good indication of the ^vind velocity aloft. 

 With Avind effects varying as W", more must be 

 known concerning the variation in wind velocities 

 m the to 200-ft range if mnd drag and wind 

 resistance are to be predicted wAth any degree of 

 accuracy. 



Probably because of the increase in boundary- 

 layer thickness 5 and in displacement thickness 

 6* (delta star) with distance downwind, the 

 direction of the wind at heights of interest to 

 boats, yachts, and ships, is not truly horizontal. 

 The wind-velocity vectors are inclined about 

 4 deg upward in the downwind direction [Curry, 

 M., "Yacht Racing," Scribner's, New York, 1948, 

 p. 131]. 



54.3 Flow Diagrams for Upper-Works Con- 

 figurations. It is regrettable that there are 

 available only a very few reasonably complete 

 diagrams for the flow of air around the hull and 

 upper works of a ship. There are fewer still of 

 these diagrams for relative-wdnd directions other 

 than directly ahead. 



A series of five diagrams of this type, rather 

 comprehensive but for ahead relative wind only, 

 are published by H. N. Prins, in an article de- 

 scribing the hull features of the Dutch passenger 

 liner Oranje [De Ingenieur, The Hague, Holland, 

 23 Jun 1939]. One of the diagrams, Plate II, is 

 redrawn and reproduced as Fig. 68. L in Sec. 68.14. 



There are a rather large number of smoke- and 

 gas-flow photographs and diagrams to be found 

 in the references listed m Sec. 68.15. 



It is possible, m fact probable, that data exist 

 for other upper-works configurations that would 

 enable additional diagrams similar to Fig. 68. L 

 to be drawn. Up to the time of writing (1955) 

 these data have not been found. 



54.4 General Formulas for the Wind Drag 

 of Irregular Ship Hulls and Superstructures. 

 Most of the older wind-drag data, pubhshed prior 

 to the 1930's, apply to a dimensional relation.ship 

 of the form 



flwiod = kAJVi 



(54. ill) 



