Ana Proceedings of the Institution of Mechanical Engineers Part M Journal of... Book review: Hydrodynamics of high-performance marine vessels, vols 1 and 2DoctorsLawrence J....
Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment 2017 / 05 Vol. 231; Iss. 2
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Book review Proc IMechE Part M: J Engineering for the Maritime Environment 2017, Vol. 231(2) 705–708 Ó IMechE 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1475090217692427 journals.sagepub.com/home/pim Book review Lawrence J Doctors. Hydrodynamics of high-performance marine vessels, vols 1 and 2. Charleston, SC: CreateSpace Independent Publishing Platform, 2015. ISBN: 1514839431; ISBN: 978151489430. Reviewed by: Philip Wilson, University of Southampton, UK DOI: 10.1080/17445302.2016.1173373 General This Magnum Opus runs to two volumes over a total of 836 pages, so it covers a huge area of research spanning from papers written in 1874, by Froude, to the date of publication of the book. This work is an essential guide to anyone new to the area of high-performance craft as well as died-in-the-wool researchers. The list of references, chapter 19, contains 76 pages of papers! To be able to track these down, for a new doctoral student, would be difficult, but Professor Doctors has now achieved that. It is noted that the use of American spelling persists throughout, no doubt reflecting the award of an Office of Naval Research (ONR) grant, which supported the production of the work. It must be said that the quality of the pictures is outstanding and that applies to the figures, which are all produced in a uniform, clear and precise manner. The attention to detail is first class; there are nearly 50 pages of contents, lists of symbols, tables, and graphical representations. Rather giving a general overview of this large work, I have summarised each chapter in the following sections. Volume 1 Chapter 1: introduction This chapter of 12 pages introduces the concept of high speed and the effects it has on the design of hulls that can achieve such speeds. The hulls can of course be monohulls, catamarans, or multi-hulls, and then, the air-supported vehicles are discussed in an overall manner, all of which are given as separate chapters in the book. Finally, as one might expect, the; re is a dimensional analysis and Froude scaling definition. Chapter 2: hydrodynamic theory This chapter of 25 pages explains the basic potential theory for water waves in deep and finite depth water. The concepts of phase velocity and group velocity are derived in a clear and consistent manner that mirrors those used in my own lecture course on fluid dynamics. What is illuminating for the practitioners to realise are the errors that can be inherent in the use of the deepwater conditions when in fact shallow water theory should be used. Therefore, subsection 2.4.2 is excellent. Chapter 3: viscous resistance This chapter of 40 pages explains how the conventional methods of naval architecture are derived for analysing the effects of viscosity on the estimation of resistive forces to forward motion. What I found useful was to have a list of all the friction lines and their associated reference papers. So, traditional Froude scaling is detailed together with methods more appropriate to multi-hulled vessels. Form factor estimation is introduced as in roughness of the wetted surface. In section 3.4, the current vogue of air lubrication is tackled showing that the work has been ongoing for 50 years or more! Equally, riblets are explained as the injections of polymers to reduce overall drag of the hull. The final part of the chapter assesses how the air drag of the water ship is estimated. Chapter 4: transom sterns This chapter of 32 pages takes the reader through some interesting ideas about why transom sterns have found favour in design. I did find the order of this chapter strange; I would have thought that it should have appeared after the final chapter on hull types. Again, the pictures in the book allow the whole aspect of transoms to be seen in the shipyard and underway. The author concludes that it allows the installation of a water jet to be easily fitted to the boat. The theoretical reasons are then given in their heads; mainly, fully ventilated flow and the conditions for ventilation are explored. The experimental validation using geosim series concludes that the free surface behind a transom stern exhibits a high degree of unsteadiness in comparison with elsewhere in the flow. This, of course, is excellent news for researchers in this area! The aspects of measuring ventilation are explored, as is the determination of the critical transom-draught Froude number. The theory is presented using linearisation with its inherent difficulties, and then, the theory moves to explore the non-linear inviscid flow models. Clearly, this is still a fruitful area for research. 706 Proc IMechE Part M: J Engineering for the Maritime Environment 231(2) Chapter 5: monohulls This chapter of 67 pages gives an insight into the whole aspect of the development of monohulls, which has dominated the high-speed marine sector. In this case, the theory of wave resistance, which by far is the major component of drag in the high-speed regime, using initially the point source travelling in deep water, the socalled thin ship theory. In particular, equation 5.52 is available for the Intrepid Designer to evaluate. This then is generalised with channels of finite depth and width. Experimental results of two geosim series are given for validation of numerical results. The numerical results at the depth Froude number of 1 are presented and compared to experimental results. After this mammoth set of work, the shallow-draught approximation is explored, and comparison is given between numerical and experimental results for the Wigley hull. With highspeed monohulls, the trend has been for more slender forms with the inherent problem of lateral instability. This has then meant that foil stabilisation has been, rather than employing side hulls, the subject of the next two chapters. The use of so-called T-foils is explored with its ability to control pitch and roll on many current catamarans. The conclusions indicate that the use of stabilisers has a small drag penalty as well as the monohulls has an advantage over catamarans in reduced hydrodynamic resistance. Chapter 6: catamarans This chapter of 22 pages explores the recent development of powered catamarans, which have developed in the past few decades. As in the previous chapters, many really excellent pictures of catamarans of various design houses are given. These show the development of the designs from relatively small displacement up to the modern very large wave-piercing designs. Again, the reader is treated to the determination of wave resistance using slender body theory, and in particular, the effects of testing in towing tanks because of wall interference. Experimental validation of the theory is given from two sources, namely, Australian Maritime College (AMC) and University of Southampton. The clear conclusion is that the linear theory gives reasonable correlation between the experiments and the theory. The interference caused by the demi-hulls is explored in terms of parallel and staggering the configuration. It seems that a good prediction can be made from linear theory for the total resistance. The staggered hulls’ superior performance is also validated. Chapter 7: trimarans and other multi-hulls This chapter of 38 pages continues from the previous discourse on multi-hulls, and the bigger trimarans are exemplified with MV Triton and USS Independence. The theories presented in the previous chapter are again used to estimate wave resistance and total resistance values. While there is a great deal of interest in this style of design, there is a paucity of experimental data in comparison with that of catamarans. Interestingly, there are figures presented using CFD software to illustrate the bow wave profile and its associated free surface. This is an area of research that is taking advantage of recent changes to CFD software. The number of side hulls is investigated, and Figure 7.14(a) indicates that monohulls have the best characteristics in that it possesses the lowest total resistance. The SWATH (Small Waterplane Area Twin Hull) hull concept is then viewed and the reader is directed to section 7.6 for some interesting conclusions. An interesting comparison of monohulls, trimaran, and sesquimaran is given. Chapter 8: air-cushioned vehicles This chapter of 83 pages explores the air-cushioned design. There are some pictures of the earliest aircushioned vehicles (ACVs) manufactured. The early development of hovercraft in the United Kingdom is explained and the development of skirts and their material properties. The change from SRN1 to the propeller-driven SRN2 is clear to see. The cutaway diagrams for the whole series of SRN is extremely instructive. The other companies which went onto develop hovercraft are shown with interesting pictures of the water jet and air propulsion VT series which were large crafts. Parallel development took place with smaller handy-sized hovercraft such as the HD series. The chapter then shows the development of hovercraft in a whole series of countries throughout the world. In fact, this is probably the most encyclopaedic set of data for ACVs that I have ever seen and is to be commended to those readers new to the craft. After 40 pages of detailed information of worldwide designs, the design of lift systems is explored in theory and, of course, the plenum chamber and annular jet flow that were favoured by many designers. The theory of a travelling pressure platform is given for the estimation of wave resistance. The familiar resistance curve with humps and hollows that give rise to the cobblestone effect is produced. Experiments were conducted by NPL, and this is a good source and review of their findings. The question of optimisation is addressed, but there are no experimental data available to validate the findings. Chapter 9: skirts and seals This chapter of 56 pages explores the remaining element not dealt with in the previous chapter, that is, that of skirts and seals. The early designs of ACVs had daylight under the hull; this of course necessitated the installation of a huge power to lift the craft and maintain equilibrium. The use of a skirt or seal to contain the air cushion was a major development. Therefore, the material and design of multi-sectioned plenum chambers have led to many varied designs. All those are explored Book review within this chapter, and as far as I can see, there is a complete that can be found of this subject. The aspects of the research reported in this chapter include the use of techniques to measure the waves within the internal chambers. The remaining problem is the wear of the skirts and seals, and data are given on this problem in Figure 9.14. The theory used allows for linearisations of pressure segments to be explored and then to derive overall estimates of wave resistance. Chapter 10: surface effect ships This chapter of 44 pages allows the reader to understand the development of what are often called sidewalled hovercraft. The various incarnations of this design are given in detail within the pictures and backed up by sufficient theory to allow those interested in this are to be able to produce design estimates for powering. The major problem is still with the flexible seals at the bow and stern and how to produce a resilient enough material to allow for daily usage. Volume 2 Chapter 11: planing craft This chapter of 60 pages takes the reader through the definitions of planing followed by a history of the development of such craft and notes that Froude’s experiments in 1875 deduced a deadrise angle of 3.3° is very similar to current craft values. The pictures in Figure 11.2 allow the reader to experience the power of such craft. The type of hullforms used for planing craft is discussed in detail and the advantages of round bilged and hard-chine forms in particular. The chapter takes the reader through the whole of current theories starting with semi-empirical methods for flat plates using much of the work of Savitsky for validation. The next topic is that of prismatic surfaces and hence into equilibrium conditions, and usefully for engineer and research student alike, some sample calculations are presented. This is followed by modifications to planing hull theory and the effects of different elements of the geometry of the vessels. The detail is immense, precise, and definitely useful to practitioners of design and the research student. I found the order of this chapter a little strange in that theories were talked about at the start and then the theory is given in detail from page 434 onwards, but at this stage, it is focussing on three-dimensional methods. The use of CFD methods is then given full rein showing how theory and experiments are converging. Optimisation is then addressed and the final section gives details of the hyper-planing vessels such as Spirit of Australia. Chapter 12: wave generation This chapter of 50 pages allows the reader to understand the wave generation characteristics in deep, 707 shallow, and width constricted situations. All of these parameters affect the height of the generated waves and in turn reflect the amount of power that a ship has to put into the water to operate at different speeds in widely varying operational conditions. The theory elaborates the velocity potential methods for defining the wave height and the wave pattern in different conditions. The effects of multi-hulls are shown to be predicted well, as is also shown in Clements et al. (2005) who were aiming at optimising a catamaran form operating on the River Thames. It is good to have the effects of viscosity, surface tension, and surface elasticity explored in some detail. The contour plots of wave terms are well presented in Figure 12.8. The work on ACVs is too brief and misses the work of PACSCAT (Partial Air Cushion Supported CATamaran), for example, the work of Clements et al. (2005) which contains contour plots of the wave system inside and outside the pressure field. The work of surface effect ships (SES) brings together nicely all the known work on wave pattern measurements, and as the author states, it is pleasing to note the good correlation between theory and experiment. As in Chapter 11, the characteristics of ship waves appear a long way into the text. I think this should have been much earlier in the chapter, since many researchers start from here. The text reinforces the theory of Laitone and Stoker and the fact that the transverse and divergent waves meet on the Kelvin line but with a phase difference of 90°. The importance of this chapter is in re-enforcing the decay rate of the wave system in both deep and shallow water. Non-linear effects are addressed for reduced depth situations and show the wall effect on wave height generation. Overall, the chapter is an excellent point for new research students to start from existing methods and experiments. Chapter 13: sinkage and trim This chapter of 32 pages deals with the prediction and experimental measurements of sinkage and trim of vessels in confined waterways. The work focuses on the regression work of Barrass and also that of Fergusson for relatively straightforward cases, but the chapter then goes on and develops the forces but without the explicit details. The theories are velocity potential methods which use work generate din the previous chapters of this book. The results of the experiments conducted on the catamaran series of Southampton are used as trial horse and conclude that the comparison could be good or indifferent depending upon the reference point used for origin of the co-ordinate system. The effect of the Froude number is clear to see in both experiments and theory, and trends are identical. The chapter then explains how ACVs have a theory that allows again give approximately similar values. For surface effect ships, the paucity of wave elevation data within the chamber does not allow comparisons with theory. The chapter finishes off with data generated for a Wigley Hull in shallow water and shows a clear agreement with 708 Proc IMechE Part M: J Engineering for the Maritime Environment 231(2) theory. Perhaps, the work of Squires (1992) and the allied work of Wu and Eatock Taylor (1989) could help with validation. Chapter 14: unsteady effects on resistance and wave generation This chapter of 38 pages covers a topic that is often neglected – unsteady effects on ship resistance and wave generation. The author sets up the problem as a second-order differential equation for all the problems that have been elucidated before, this ship theory, pressure fields, and SES craft. The solutions are presented, for example, in equation 14.15 on page 551. The problem then is the interpretation of the last two terms and how accurate can these be evaluated numerically. As far as I can tell, the methods are complete, as I would expect, and sufficient information is given, for example, using the steady-state limits to gain confidence in the answers. The main problem is the lack of reported experimental data, but where do they exist? The trends are good and in some cases very close indeed to the numerics. The aspects of this chapter that are rarely reported are those associated with manoeuvring in such cases. The equations 14.62 and 14.63 will go a long way to help designers and researchers in this area. Chapter 15: motions of displacement vessels in waves This chapter of 44 pages allows the reader to understand the current level of knowledge in this area of research of displacement vessels in a seaway. The results from theory and experiments in general have good agreement for heave and pitch and for the later plane motions; the answers are tolerable if a reasonable estimate of roll damping can be made. There is a much longer text available in Lloyd, Ship response in a seaway. The biggest experimental challenge will be with ships and ship models that have stabilisation using Tfoils or some akin to this stabiliser. The biggest differences seem to be with measurement of wave height, see Figure 14.22(c). Chapter 16: motions of nondisplacement vessels in waves This chapter of 42 pages is a continuation of the previous chapter, but for ACVs, SES, and planing craft, and a good source of data for verification of numerical methods. Chapter 17: afterword This final chapter of 17 pages contains extra experimental resistance data that apply to various studies within the other chapters. The author also discusses an alternative measure of the resistance of a vessel in terms of the transport factor. Chapter 18: appendix This contains a dictionary of ship terms and usefully for many a reminder of many mathematical relationships, from Pythagoras’ Theorem, cosine, and sine integral Wehausen wave functions. Thus, to summarise an excellent book in two volumes will be a source for a wide variety of engineers, new or old to designing highperformance marine vessels, as well as doctoral research students and many current researchers in this active field of study. References 1. Clements, R.J., Wilson, P. A, Lewthwaite, J.C., Molland, A.F., Ivanov, P. The potential for the use of a novel craft, PACSCAT (partial air cushioned supported catamaran) in inland European waterways. Proceedings of FAST2005, St Petersburg, Russia, 2005. 2. Squires, M.A., An investigation on the static and dynamic swell up effect for ship motions. Ph.D. thesis, University of Southampton, 1992. 3. Wu, G. X., Eatock Taylor, R. A Green’s function for ship motions with forward speed. Journal of Ship Research, Volume 34, 1989.