Asymptotic Formulation for an Acoustically Driven Field Inside a Rectangular Cavity With a Well-Defined Convective Mean Flow Motion

A Novel Investigation of the Oscillatory Field Over a Transpiring Surface

“…Figure 13 gives the actual velocity and pressure traces from which the experimental amplitudes shown in Figure 12 were taken when the hot "lm was positioned 8 mm above the transpiring wall. In particular, when using the two-dimensional timedependent solutions provided by Majdalani for a rectangular geometry [11], an excellent agreement is found to exist between analytical predictions and experimental results.…”

“…Such results are consistent with the "ndings of Beddini et al [16}18] and Yang et al [19}21] who reported, with the onset of turbulence, vortical damping in both amplitude and penetration. The small discrepancy between our experimentally measured overshoot and that predicted theoretically by Majdalani [11] can be attributed, in most part, to the experimental error. This error stems from uncertainties in measuring the injection speed of CO , kinematic viscosity of the gas around the hot "lm, location of the hot "lm, and actual oscillation frequency.…”

“…This is captured experimentally by placing the hot "lm inside the Stokes boundary layer region. As shown by several researchers, including Flandro [14], and Majdalani [10,11], a two-dimensional time-dependent "eld is more adequate to describe the #ow velocity inside the laminar boundary layer. One important phenomenon exhibited by the velocity pro"le inside the boundary layer is the presence of a so-called Richardson overshoot near the wall [15].…”

“…This error stems from uncertainties in measuring the injection speed of CO , kinematic viscosity of the gas around the hot "lm, location of the hot "lm, and actual oscillation frequency. All of these parameters are needed to determine the exact amount of overshoot (see Majdalani [11] for a detailed discussion of the overshoot phenomenon). As shown in Figure 12, the experimentally measured amplitudes are larger than the one-dimensional wave amplitudes, and thus in agreement with current theories.…”

“…The "rst improvement is achieved by utilizing a Scotch-yoke mechanism to replace the slider-crank mechanism that was used previously. Another purpose of this investigation is to compare experimental data to predictions derived from analytical models of the #ow"eld by Majdalani [10,11].…”