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Fluid Dynamics
Published in Wen-Jei Yang, Handbook of Flow Visualization, 2018
Tsuyoshi Asanuma, Yoshimichi Tanida
If an aerofoil of the same profile is placed in compressible flow at the same angle of attack, the pressure coefficient, lift coefficient, and moment coefficient are all affected by the Mach number in proportion to the factor 1/√1 − M2. For example, the pressure coefficients Cp= (p − p∞)/½ρU2, in which p∞ is the pressure of the free stream, are related by CpM=11−M2Cp0(Prandtl−GlauertRule)
What do we Measure, and Why?
Published in Richard J. Goldstein, Fluid Mechanics Measurements, 2017
To correlate data, V is typically measured with a Pitot or Prandtl tube, and the temperature and pressure are determined with appropriate instrumentation (see Chap. 2). The forces and moments on the model are usually determined with a specially designed balance. The density is usually computed from the measured temperature and pressure. Typical wind-tunnel data are shown in Fig. 1.3. These data, adapted from National Advisory Committee for Aeronautics (NACA) data for an airfoil section, display the variation of section lift coefficient and moment coefficient, defined as () Cl=L12ρU2c
Experimental facilities
Published in Stefano Discetti, Andrea Ianiro, Experimental Aerodynamics, 2017
Following the formulation of [11], the corrections of angle of attack (in radians), lift coefficient, and moment coefficient read as Δαsc=12πσ(CLu+4CM(1/4)u)ΔCLsc=−σCLuΔCM(1/4)sc=−σ4ΔCLsc where CLu and CM(1/4)u are the uncorrected lift coefficient and moment coefficient with respect to the quarter chord, respectively.
Investigation of the elliptical resonant vibration of high-rise buildings induced by the oblique-downwind interference effects
Published in Journal of Asian Architecture and Building Engineering, 2023
Yuan-Lung Lo, Cheng-Wei Chen, Cheng-Hsin Chang, Yi-Chao Li
In Equations (1), and are measured instantaneous base forces and moments as indicated in Figure 4. For a high-rise building, is usually ignored, and is the twisting loading along the vertical z-axes of a high-rise building. The overturning moment is linearly related to the base force , as well as to . The force coefficient of is calculated by normalizing the measured base force by the reference force, , where the velocity pressure (pa) with the air density in kg/m3 and the mean wind speed at the model height in m/s. is the projected area in m2 of the windward face. Same as the force coefficient, the moment coefficient is calculated by normalizing the measured overturning moment by the reference moment, .