| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
Pressure fluctuation was measured in a turbulent jet using a condenser microphone and piezoresistive transducer. The power-law exponent and proportional constant of normalized pressure spectrum are discussed from the standpoint of Kolmogorov universal scaling. The clear power-law with scaling exponent close to -7/3 was confirmed in the range of 600<R_λ. These Reynolds numbers are much larger than those in velocity fluctuation to achieve Kolmogorov scaling. The spectral constant is not universal but depends on Reynolds numbers. Measured pressure PDFs are compared with direct numerical simulation.
New methods and improved measurement techniques are thus sought for. In this study, both static pressure and wall pressure in turbulent boundary layers have been measured simultaneously by using small transducer and microphone. Obtained results may be summarized as follows.
(1)The root mean square of vertical velocity component is evaluated by means of mean pressure distribution The profile is su
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fficiently agree with the result obtained by direct v-component velocity measurement.
The peak location of v^+ is scaled as a function of Reynolds number ; y_p^+=0.00135 times R_θ^1.42.
(2)Root mean square of wall pressure, normalized by inner variable, indicates an increasing function of R_θ ; p_rms^+∝R_θ^0.28. This trend is similar with the result by DNS.
(3)The distribution of static pressure r.m.s., p_rms^+, across the boundary layer does not show the Reynolds number scaling. If p_rms^+ is averaged within the log-region, its Reynolds number dependence is approximated by the power-law ; p_rms^+∝R_θ^0.32. This Reynolds number dependence is much stronger than that of stream-wise velocity or vertical velocity component.
(4)The correlation between wall and static pressure across the boundary layer indicates the positive value. The distribution of correlation coefficient does not show the Reynolds number dependence if the distance from the wall is normalized by Δ for R_θ>7000.
(5)In relation to streamwise velocity u, the root mean square of static pressure is scaled by ρu_rms^2. The ratio p_rms/ρu_rms^2 is the order of 1 in the inner region. The correlation between the pressure and streamwise velocity indicates the local minimum and maximum value at y/Δ=0.05 and y/Δ=0.2,respectively. In the outer region, 0.25<y/Δ, the correlation becomes negative. These trends are observed in DNS. Less
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