Flow and Performance Characteristics of S- Shaped Diffuser


  • Sonal Lalchandani Department of Mechanical Engineering, Government Engineering College, Bilaspur, Chhattisgarh, India-495009
  • G. K. Agrawal Dept. of Mech. Engg. Govt. Engg. College Bilaspur, C. G.


Airflow, Pressure recovery coefficient, Turn angle, S-Shaped diffusers.


This paper presents the effect of turning angle on the first and second curvature of S-shaped diffusers, one with a square inlet and rectangular outlet having a centre length of 800 mm and an area ratio of 2.5. A computer program based on the finite volume technique, using the Standard k–ε turbulence model, has been adopted and modified to predict the flow. The measurements of pressure distributions of the airflow in S-shaped diffusers are performed for twelve models of different turn angles such as 30º/30º, 60º/ 60º, 90º/ 90º, 120º/ 120º, 150º/ 150º, 180º/ 180º, 60º/90º, 90º/ 60º, 90º/ 120º, 120º/ 90º, 120º/ 150º, 150º/ 120º. In this paper, results are shown in the form of pressure recovery coefficient and pressure recovery efficiency. Furthermore, pressure and velocity contours have been developed for the entire study of all twelve designs of the diffuser. The results showed that the diffuser pressure recovery coefficient is strongly affected by the geometrical parameters of the S-shaped diffuser and inflow Reynolds number. The turning angle plays an important role in improving the S-shaped diffuser's performance. In this study it is concluded that diffuser 90º/ 120º performs best, it gives the highest pressure recovery coefficient and efficiency, whereas diffuser 30º/30º gives the lowest performance parameters.


Agrawal, G.K. and Powle, U.S., “Investigation on

Flow Through S-Shaped Diffusers”, in: Proc. of 6th

International and 43rd National Conference on FMFP,

MNNITA, Allahabad, U.P., India, 2016.

Agrawal, G.K. and Powle, U.S, “Performance

Analysis on Flow Through S-Shaped Diffuser”,

Journal of CSVTU, Vol. 8(2), PP.129- 136, 2019.

Agrawal, G.K. and Powle, U.S, “Investigation on

Flow Through Curved Diffuser”, in: Proc. of

th National Conference on FMFP, NIT Hamirpur

, Himachal Pradesh, India, 2013.

Agrawal, G.K. and Powle, U.S, “Comparitive

Analysis of S-Shaped Curved Diffuser”, in: Proc.

of National Conference on Infrastructure

Development and Sustainability, GEC Bilaspur, 2018

Anand, R.B., Rai, L. and Singh, S.N., “Flow and

Performance Characteristics of 22.5º/22.5º S- Shaped

Circular Diffuser”, in: Proc. of 28th National

Conference on FMEP, Chandigarh, India, 2001.

Anand, R.B., Rai, L., Singh, S.N., Sharma, O.P.,

“Flow Characteristics of a low aspect ratio

º/90º S-Shaped Diffuser”, Journal of Aeronautical

Society of India 53 (2001).

Reneau, L. R., Johnston, J. P. and Kline, S. J.,

“Performance and Design of Straight, Two–

Diffusers”, Journal of Basic Engineering,

Transactions of the ASME, Vol. 89, PP. 141-150,

(March 1967)

McMillan, O. J., "Mean-Flow Measurements of the

Flow Field Diffusing Bend", NASA Contractor

Report 3634, (1982).

Gupta, V., Devpura, R., Singh, S. N. and Seshadri,

V., “Effect of Aspect Ratio and Curvature on

Characteristics of S-Shaped Diffusers”, Indian Journal

of Engineering & Materials Sciences,

Vol. 8, PP. 141-148, (June 2001).

Gopaliya, M.K., Kumar, M., Kumar, S. and

Gopaliya,S.M., “Analysis of Performance

characteristics of the S-shaped diffuser

with offset”, Journal of Aerospace Science and

Technology, 11, 130–135 (2006).


Gopaliya, M.K.,Goel, P., Prashar, S. and Dutt, A.,

“CFD Analysis of Performance Characteristics

of S-Shaped Diffusers with Combined Horizontal

and Vertical Offsets”, Journal of Computers

and Fluids, 40, PP. 280-290, (2011)

Sullerey, R.K., Chandra, B. and Muralindhar, V.,

“Performance comparison of straight and curved

diffusers”, Def. Sci. J. 33(3),195–203 (2014)

Sinha, P. K., Seshadri, V., Chandel, S. and Gaikwad,

M., “Analysis of the Improvement in Performance

Characteristics of S-Shaped Rectangular Diffuser

by Momentum Injection Using Computational Fluid

Dynamics”, Engineering Applications of

Computational Fluid Mechanics, Vol. 3, No. 1, PP.


Gupta, A., Singh, H. and Raghav, A.K., “Effect of

Change in the Curvature of Flow and Performance

Characteristics of Straight and S- shaped Diffuser”,

Journal of The institution of Engineers (India),

July 2020. https://doi.org/10.1007/s40032-020-


Som, S.K., Agrawal G.K. and Chakraborty, S.,

“Thermodynamics of Flame Impingement Heat

Transfer”, Journal of Applied Physics 102, (2007).




How to Cite

Lalchandani, S., & Agrawal, G. K. (2023). Flow and Performance Characteristics of S- Shaped Diffuser. CSVTU Research Journal, 11(02), 48–57. Retrieved from https://csvtujournal.in/index.php/rjet/article/view/200