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Abstract
The paper presents a detailed study of the performance of fully developed subsonic turbulent flow in a circular cross-section S-shaped centerline-diffusing duct. A precalibrated 5-hole pressure probe was used for the measurements. The diffuser cross-section was expanded to 2.25 area ratio (Ar) at the exit. The duct was fabricated by joining two 22.5º bends of curvature ratio (βt) 11.46 in reverse direction with a centerline offset of 0.2 of the axial length of the diffuser. The test was carried out with inlet Re=8.4x105, calculated based on diffuser inlet diameter. The experimental results indicated the generation of secondary flow in the form of a pair of counter rotating vortices in the first half, which changes its senses of rotation in the second half. The overall static pressure recovery of the diffuser was 40%.
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References
- Rowe, M., "Measurements and Computation of Flow in Pipe Bends", Journal of Fluid Mechanics, Vol.43, Part 4, 1970, pp.771-783.
- Bansod, P. and Bradsaw, P., "The Flow in S-shaped Ducts", Aeronautical Quarterly, Vol.23, Part 2,1972, pp.131-140.
- Butz, L. A., "Turbulent Flow in S-shaped Ducts", M.S. Thesis, 1979, Prudue University, U. S. A.
- Taylor, A. M. K. P., Whitelaw, J. H. and Yianneskis, M., "Developing Flow in S-shaped Ducts, Part II Circular Cross-section", NASA Contract Report 3759, 1984.
- Rojas, J., Whitelaw, J. H. and Yianneskis, M., "Developing Flow in S-shaped Diffuser, Part II - Circular Cross-section Diffuser, NASA Contract Report FS/83/28, 1983.
- Guo, R. W. and Seddon, J., "Swirl Characteristics of an S-shaped Air Intake With Both Horizontal and Vertical Offsets" Aeronautical Quarterly, 1984, pp. 117-127.
- Whitelaw, J. H. and Yu, S. C. M., "Turbulent Flow Characteristics in an S-shaped Diffusing Duct", Flow Measurement and Instrumentation, Vol. 4, No.3, 1993, pp.171-179.
- Shimuzu, Y., Nagafusa, M., Sugino, K. and Kubota, T., "Studies on Performance and Internal Flow of U-shaped and Snake-shaped Bend Diffuser", Second Report, ASME, Journal of Fluid Engineering, Vol.108, 1986, pp. 297- 303.
- Majumder, B., Singh, S. N. and Agrawal, D. P., "Flow Characteristics in S-shaped Diffusing Duct", International Journal of Turbo and Jet Engines, Vol.14, 1997, pp. 45-57.
- Sullery, R. K., Chandra, B. and Murlidhar., "Performance Comparison of Straight and Curved Diffuser",
- Defence Scientific Journal, Vol.33, No.3, 1983, pp.195-203.
- Sonoda, T., Arima, T. and Oana, M., "The Influence of Downstream Passage on the Flow within an Annular S-shaped Duct", ASME, Journal of Turbomachinery, Vol.120, 1998, pp.714-722.
- Fox, R. W. and Kline, S. J., "Flow Regimes in Curved Subsonic Diffuser" ASME, Journal of Basic Engineering, 1962, pp. 303-316.
- McMillan, O. J., "Mean Flow Measurements of the Flow Diffusing Bend", NASA Contract Report 3634,
- Mullick, A. N., "Turbulent Flow Investigation in an S-shaped Diffusing Duct" M. E. Thesis, Jadavpur University, India, 2000.
- Kline, S. J., "The Purpose of Uncertainty Analysis" ASME, Journal of Fluid Engineering, Vol. 107, 1985, pp.153-160.
- Yu, S. C. M., "Turbulent Flow Calculation in S-shaped Diffusing Ducts using a Viscous Marching Technique", VIth International Conference on Computational Methods and Experimental Measurements, 1993, Vol.1, Heat and Fluid Flow.
References
Rowe, M., "Measurements and Computation of Flow in Pipe Bends", Journal of Fluid Mechanics, Vol.43, Part 4, 1970, pp.771-783.
Bansod, P. and Bradsaw, P., "The Flow in S-shaped Ducts", Aeronautical Quarterly, Vol.23, Part 2,1972, pp.131-140.
Butz, L. A., "Turbulent Flow in S-shaped Ducts", M.S. Thesis, 1979, Prudue University, U. S. A.
Taylor, A. M. K. P., Whitelaw, J. H. and Yianneskis, M., "Developing Flow in S-shaped Ducts, Part II Circular Cross-section", NASA Contract Report 3759, 1984.
Rojas, J., Whitelaw, J. H. and Yianneskis, M., "Developing Flow in S-shaped Diffuser, Part II - Circular Cross-section Diffuser, NASA Contract Report FS/83/28, 1983.
Guo, R. W. and Seddon, J., "Swirl Characteristics of an S-shaped Air Intake With Both Horizontal and Vertical Offsets" Aeronautical Quarterly, 1984, pp. 117-127.
Whitelaw, J. H. and Yu, S. C. M., "Turbulent Flow Characteristics in an S-shaped Diffusing Duct", Flow Measurement and Instrumentation, Vol. 4, No.3, 1993, pp.171-179.
Shimuzu, Y., Nagafusa, M., Sugino, K. and Kubota, T., "Studies on Performance and Internal Flow of U-shaped and Snake-shaped Bend Diffuser", Second Report, ASME, Journal of Fluid Engineering, Vol.108, 1986, pp. 297- 303.
Majumder, B., Singh, S. N. and Agrawal, D. P., "Flow Characteristics in S-shaped Diffusing Duct", International Journal of Turbo and Jet Engines, Vol.14, 1997, pp. 45-57.
Sullery, R. K., Chandra, B. and Murlidhar., "Performance Comparison of Straight and Curved Diffuser",
Defence Scientific Journal, Vol.33, No.3, 1983, pp.195-203.
Sonoda, T., Arima, T. and Oana, M., "The Influence of Downstream Passage on the Flow within an Annular S-shaped Duct", ASME, Journal of Turbomachinery, Vol.120, 1998, pp.714-722.
Fox, R. W. and Kline, S. J., "Flow Regimes in Curved Subsonic Diffuser" ASME, Journal of Basic Engineering, 1962, pp. 303-316.
McMillan, O. J., "Mean Flow Measurements of the Flow Diffusing Bend", NASA Contract Report 3634,
Mullick, A. N., "Turbulent Flow Investigation in an S-shaped Diffusing Duct" M. E. Thesis, Jadavpur University, India, 2000.
Kline, S. J., "The Purpose of Uncertainty Analysis" ASME, Journal of Fluid Engineering, Vol. 107, 1985, pp.153-160.
Yu, S. C. M., "Turbulent Flow Calculation in S-shaped Diffusing Ducts using a Viscous Marching Technique", VIth International Conference on Computational Methods and Experimental Measurements, 1993, Vol.1, Heat and Fluid Flow.