8 Measurement of Aerodynamic Forces and Moments . . . . . . . . . . . . 183
8.1 The Aerodynamic Forces and Moments . . . . . . . . . . . . . . . . . . 183
8.2 Aerodynamic Balances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
8.2.1 Forces and Strain Gauges . . . . . . . . . . . . . . . . . . . . . . 185
8.2.2 Sting Type Force Balance . . . . . . . . . . . . . . . . . . . . . . 188
8.2.3 Force Balance by Direct Force Measurements . . . . . . . 190
8.2.4 Balance for Ground Vehicle . . . . . . . . . . . . . . . . . . . . 193
8.3 Drag Determination from Wake Survey . . . . . . . . . . . . . . . . . . 195
9 Characterisation of Flow Properties at the Surface . . . . . . . . . . . . . 199
9.1 The Action of a Fluid at the Wall . . . . . . . . . . . . . . . . . . . . . . 199
9.2 Measurement of Pressure at the Wall . . . . . . . . . . . . . . . . . . . . 200
9.2.1 Pressure Scanning Systems . . . . . . . . . . . . . . . . . . . . . 200
9.2.2 Types of Pressure Transducers . . . . . . . . . . . . . . . . . . 201
9.2.3 Sensitivity and Response Time . . . . . . . . . . . . . . . . . . 205
9.3 Pressure Sensitive Paint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
9.3.1 Principle and Composition of the Pressure Sensitive
Paint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
9.3.2 Relation Between the Pressure and the Luminous
Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
9.3.3 Main Areas of Application of the PSP . . . . . . . . . . . . . 208
9.3.4 Developments in the Field of PSP . . . . . . . . . . . . . . . . 211
9.4 Skin Friction Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
9.4.1 Floating Element Balance . . . . . . . . . . . . . . . . . . . . . . 212
9.4.2 Hot Film Surface Gauge . . . . . . . . . . . . . . . . . . . . . . . 212
9.4.3 Stanton and Preston Tubes . . . . . . . . . . . . . . . . . . . . . 213
9.4.4 Oil Film Interferometry . . . . . . . . . . . . . . . . . . . . . . . 213
9.4.5 Liquid Crystals Thermography . . . . . . . . . . . . . . . . . . 215
9.4.6 Adjustment Based on the Logarithmic Law
of Turbulent Boundary Layers . . . . . . . . . . . . . . . . . . 215
9.5 Measurement of the Wall Heat Transfer . . . . . . . . . . . . . . . . . . 217
9.5.1 Calorimetric Techniques . . . . . . . . . . . . . . . . . . . . . . . 217
9.5.2 Thermo-Sensitive Paints . . . . . . . . . . . . . . . . . . . . . . . 219
9.5.3 Infrared Thermography . . . . . . . . . . . . . . . . . . . . . . . . 221
9.6 Measurement of Deformations of the Models . . . . . . . . . . . . . . 224
10 Intrusive Measurement Techniques . . . . . . . . . . . . . . . . . . . . . . . . . 225
10.1 Solid Probes: Benefits and Limitations . . . . . . . . . . . . . . . . . . . 225
10.2 Pressure Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
10.2.1 Measurement of Stagnation or Total Pressure,
Pitot Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
10.2.2 Measurement Using Pitot-Static or Prandtl Probe . . . . . 227
10.2.3 Multi-holes Probe to Resolve the Direction of the
Velocity Vector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
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