Authors : Ulvi Fatullayev

Volume/Issue : Volume 10 - 2025, Issue 5 - May

Google Scholar : https://tinyurl.com/5n79rpfh

DOI : https://doi.org/10.38124/ijisrt/25may2074

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

Abstract : This study presents the validation of a computational method for predicting flow characteristics in the exhaust of a low-pressure steam turbine, with specific focus on modeling the last stage and exhaust hood as an integrated system. Using the ANSYS CFX solver, numerical simulations were carried out on both a one-passage model and a full-geometry model, including variations in tip clearance, mesh density, and interface treatment. Experimental data from a scaled turbine model at ITSM Stuttgart were used for validation. The study investigates the influence of rotor tip clearance, mesh refinement strategies, and circumferential non-uniformities on diffuser and exhaust hood performance. Simulation results were benchmarked against measurements under different operating conditions—part load, design, and overload. After validating the computational method, it was applied to a Siemens-type single side exhaust hood to evaluate performance and identify loss mechanisms. The findings support the feasibility of the Last Stage Modeling (LSM) approach and offer optimization insights for future low-pressure steam turbine designs.

Keywords : Steam Turbine, Exhaust Hood, Diffuser, CFD, Validation, Tip Clearance, Pressure Recovery, Mesh Sensitivity.

References :

1. Polklas, Thomas. Essen : s.n., May 2004, Universität Duisburg Essen, Dissertation.“Entwicklung eines numerischen Verfahrens zur strömungsmechanischen Auslegung des Abströmgehäuses einer Niderdruck-Dampfturbine.”
2. Hurtado, Fernando Sandro Velasco, Maliska, Clovis Raimundo und Cordazzo, Jonas. 2005. CILAMCE 2005 “An Element-based Finite Volume Formulation for Reservoir Simulation. ”
3. Moore, M.J. “Aerothermodynamics of Low Pressure Steam Turbines and Condensers.”
4. Otterfing 1998 Siemens-intern “Technical Report AEAT/TR-98-11 Berechnung des dreidimensionalen Strömungsfeldes in Modellturbinenstufen mit CFX-TASCflow.”
5. Denton, J.D. “The calculation of three-dimensional viscous flow through multistage turbomachines.” 1992, Transactions of the ASME, Journal of turbomachinery, Bd. 114, S. 18-26.
6. Denton, J.D. “Computational Methods for Turbomachninery Flow.” 1986. ASME Course Fluid Dynamics Turbomachinery, Lecture 9, P. 13-1 to 13-41.
7. Denton, J.D. “Loss Mechanismus in Turbomachines. ” 1993, ASME Journal of Turbomachinery, Bd. 115, S. 621-656.
8. Gloss, Dr. D. “Replacing the “Coupling Tool” by Last Stage Modeling for calculating exhaust steam flow”. Siemens-Intern.
9. ITSM Presentation "Cp-Wert Diffusor.ppt".