Page 14 - Aerodynamics for Engineering Students

Contents xi

8.3.5 Use of multi-element aerofoils on racing cars 498
8.3.6 Gurney flaps 500
8.3.7 Movable flaps: artificial bird feathers 504
8.4 Boundary layer control for the prevention of separation 505
8.4.1 Boundary-layer suction 505
8.4.2 Control by tangential blowing 507
8.4.3 Other methods of separation control 512
8.5 Reduction of skin-friction drag 514
8.5.1 Laminar flow control by boundary-layer suction 515
8.5.2 Compliant walls: artificial dolphin skins 517
8.5.3 Riblets 520
8.6 Reduction of form drag 522
8.7 Reduction of induced drag 522
8.8 Reduction of wave drag 525

9 Propellers and propulsion 527
Preamble 527
9.1 Froude’s momentum theory of propulsion 527
9.2 Airscrew coefficients 533
9.2.1 Thrust coefficient 533
9.2.2 Torque coefficient 534
9.2.3 Efficiency 535
9.2.4 Power coefficient 535
9.2.5 Activity factor 535
9.3 Airscrew pitch 538
9.3.1 Geometric pitch 539
9.3.2 Experimental mean pitch 539
9.3.3 Effect of geometric pitch on airscrew performance 539
9.4 Blade element theory 54 1
9.4.1 The vortex system of an airscrew 54 1
9.4.2 The performance of a blade element 542
9.5 The momentum theory applied to the helicopter rotor 549
9.5.1 The actuator disc in hovering flight 549
9.5.2 Vertical climbing flight 550
9.5.3 Slow, powered, descending flight 550
9.5.4 Translational helicopter flight 551
9.6 The rocket motor 552
9.6.1 The free motion of a rocket-propelled body 554
9.7 The hovercraft 558
Exercises 56 1

Appendix 1: symbols and notation 563
Appendix 2: the international standard atmosphere 567
Appendix 3: a solution of integrals of the type of Glauert’s integral 569
Appendix 4: conversion of imperial units to systkme
international (SI) units 572
Bibliography 574
Index 577