# Rotor Blade Sweep Effect on the Performance of a Small Axial Supersonic Impulse Turbine

Jeong, Sooin;Choi, Byoungik;Kim, Kuisoon

• Accepted : 2015.12.10
• Published : 2015.12.30
• 23 6

#### Abstract

In this paper, a computational study was conducted in order to investigate the rotor blade sweep effect on the aerodynamics of a small axial supersonic impulse turbine stage. For this purpose, three-dimensional unsteady RANS simulations have been performed with three different rotor blade sweep angles ($-15^{\circ}$, $0^{\circ}$, $+15^{\circ}$) and the results were compared with each other. Both NTG (No tip gap) and WTG (With tip gap) models were applied to examine the effect on tip leakage flow. As a result of the simulation, the positive sweep model ($+15^{\circ}$) showed better performance in relative flow angle, Mach number distribution, entropy rise, and tip leakage mass flow rate compared with no sweep model. With the blade static pressure distribution result, the positive sweep model showed that hub and tip loading was increased and midspan loading was reduced compared with no sweep model while the negative sweep model ($-15^{\circ}$) showed the opposite result. The positive sweep model also showed a good aerodynamic performance around the hub region compared with other models. Overall, the positive sweep angle enhanced the turbine efficiency.

#### References

1. Lewis, R. and Hill, J., "The Influence of Sweep and Dihedral in Turbomachinery Blade Rows", Journal of mechanical Engineering Science, Vol. 13, No. 4, 1971, pp.266-285. DOI:10.1243/JMES_JOUR_1971_013_043_02 https://doi.org/10.1243/JMES_JOUR_1971_013_043_02
2. Hill, J. and Lewis, R., "Experimental Investigations of Strongly Swept Turbine Cascades with Low Speed Flow", Journal of mechanical Engineering Science, Vol. 16, No. 1, 1974, pp. 32-40. DOI:10.1243/JMES_JOUR_1974_016_007_02 https://doi.org/10.1243/JMES_JOUR_1974_016_007_02
3. Denton, J. and Xu, L., "The Exploitation of Threedimensional Flow in Turbomachinery Design", Proceedings of the Institution of Mechanical Engineers, Part C, Journal of Mechanical Engineering Science, Vol. 213, No. 2, 1999, pp. 125-137. DOI:10.1243/0954406991522220 https://doi.org/10.1243/0954406991522220
4. Wadia, A., Szucs, P. and Crall, D., "Inner Workings of Aerodynamic Sweep", ASME Journal of Turbomachinery, Vol. 120, 1998, pp. 671-682. DOI:10.1115/1.2841776 https://doi.org/10.1115/1.2841776
5. Gümmer, V., Wenger, U. and Kau, H., "Using Sweep and Dihedral to Control Three-Dimensional Flow in Transonic Stators of Axial Compressors", ASME Journal of Turbomachinery, Vol. 123, 2001, pp. 40-48. DOI:10.1115/1.1330268 https://doi.org/10.1115/1.1330268
6. Denton, J., "The Effects of Lean and Sweep on Transonic Fan Performance: A Computational Study", TASK QUARTERLY, Vol. 6, No. 1, 2002, pp. 7-23.
7. Pullan, G. and Harvey, N. W., "Influence of Sweep on Axial Flow Turbine Aerodynamics at Midspan", ASME Journal of Turbomachinery, Vol. 129, No. 3, 2007, pp. 591-598. DOI:10.1115/1.2472397 https://doi.org/10.1115/1.2472397
8. Pullan, G. and Harvey, N. W., "Influence of Sweep on Axial Flow Turbine Aerodynamics in the Endwall Region", ASME Journal of Turbomachinery, Vol. 130, No. 4, 2008, pp. 041011-1-041011-10. DOI:10.1115/1.2812337 https://doi.org/10.1115/1.2812337
9. Yoon, S., Denton, J., Curtis, E., Longley, J. and Pullan, G., "Improving Intermediate Pressure Turbine Performance by Using a Nonorthogonal Stator", ASME Journal of Turbomachinery, Vol. 136, No. 1, 2014, pp. 021012-1-021012-8. DOI:10.1115/1.4023941 https://doi.org/10.1115/1.4023941
10. Hah, C. and Shin, H., "Study of Near-Stall Flow Behavior in a Modern Transonic Fan with Compound Sweep", ASME Journal of Fluid Engineering, Vol. 134, 2012, pp. 071101-1-071101-7 DOI:10.1115/1.4006878 https://doi.org/10.1115/1.4006878
11. Menter, F. R., "Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications", AIAA Journal, Vol. 32, No. 8, 1994, pp. 1598-1605. DOI:10.2514/3.12149 https://doi.org/10.2514/3.12149
12. Moffitt, T. P., "Design and Experimental Investigation of a Single-Stage Turbine with a Rotor Entering Relative Mach Number of 2", NACA RM E58F20a, 1958.
13. Moffitt, T. P. and Klag, F. W., Jr., "Experimental Investigation of Partial- and Full-Admission Characteristics of a Two-Stage Velocity Compounded ", NASA TM X-410, 1960

#### Acknowledgement

Supported by : Pusan National University