The paper presents some recent new data on the combined eflects of pressure gradient and9eestream turbulence level on the onset and length of tho latter stages of the boundary layer transition process. Generalized correlations for the transition length Reynolds number are developed from considerations of the non-dimensional turbulent spot formation rate. The optimized correlation is built into a popular linear combination integral computer code to predict the growth of the transitional boundary layer in a number of practical engineeringflows. NOTATION

List of courses and conferences attended IV Acknovle dgemen t s V Nomenclature VI Contents IX List of figures in the main text XIII List of figures in Appendix 6. XVI Objectives of the current research. 1 Chapter 1 .-Historical development and Introduction Chanter 2.-Experimental facilities, A. 3.6 Lot-7 Reynolds number effects 77 3.7 Equilibrium and self-preserving boundary layers 79 3.8 Flow two-dimensionality by the "momentum balance" test 82 3.9 Esti.mation of the entrainment rate 83 Chapter 4.-Details of experiments conducted and discussion of results # 89-127 4.1 Experimental test boundary layers 90 4.2 Transition Reynolds numbers downstream of a two-dimensional trip wire 93 4.3 Statistical similarity of transition regions 94 4.4 Transitional mean and fluctuating velocity profile similarity 96 4.5 Transitional local skin friction coefficient similarity 98 4.6 Description of the transition region 4.7 Correlations of transition length Reynolds number 4.8 Flow visualisation studies 4.9 Intermittency profiles through transition 4.10 Spanwise variation in the boundary layer 4.11 Entrainment rates 4.12 Turbulent boundary layer development Chapter 5. Calculation of transitional boundary layers 128-141 5.1 Introduction 5.2 Transition model A. 130 5.3 Transition model B. 134 5.4 Comparison of models A and 3. 135 I Conclusions 142 Suggestions for further work 146 References 148 Appendix 1 .-Experimental apparatus 1 .!-1.3 Appendix 2.-Experimental uncertainty in integral thicknesses 2.1-2.3 Appendix 3.-Computer programs and flow charts 3.1-3.22 Appendix 4.-Development of a general relationship for estimating the transitional boundary layer skin friction coefficient 4.1-4.7 Appendix 5.-Integral prediction methods for laminar and turbulent boundary layers.

This paper outlines a number of different applications of spreadsheet solutions to mechanical engineering problems involving ideal fluid flow, two-dimensional heat transfer, plate bending and torsion of non-circular sections. The general utility of a spreadsheet in handling finite difference equations is further illustrated in an application to simulate the dynamic response of a DC voltage controlled servo-motor. Finally, since most spreadsheets also incorporate the common logical operators then any arbitrary Boolean function can be manipulated with any range of input logic states. Details are therefore included in the paper on the application of a spreadsheet to simulate and test the operation of a prototype digital logic circuit. The educational advantages in using a spreadsheet are highlighted in the variety of engineering problems which can be solved without having to resort to the specialist and generally more expensive finite element software packages.

The paper presents the results of an experimental investigation aimed at an elucidation of the individual and collective influence of freestream turbulence intensity and pressure gradient on the length of the transitional boundary layer. A correlation for the transition length Reynolds number is developed and used, in an intermittency-based computational scheme, to predict the transitional boundary layer behaviour in a number of practical flows representative of the suction surface of gas turbine blading.

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