Session: 35-01 CFD Analyses

Paper Number: 83387

83387 - Influence of the Convergent-Divergent Nozzles Arrangement Parameters on Aerodynamic Losses and Overall Supersonic Turbine Performance 

Single-stage axial pressure compound and two-row velocity compound supersonic turbines have a very high specific work, which allows having high power levels at high-pressure ratios and small flow rates in a very compact dimensional envelope. The latter is extremely desirable in certain types of Liquid Rocket Engine (LRE) turbopumps. Besides, the compactness, mechanical simplicity, and low cost of such turbines are favorable in high-pressure ratio Organic Rankine Cycles (ORC), gas expanders in chemical and technological processes, various mechanical drive applications, etc. However, despite their mechanical simplicity, the supersonic aerodynamic effects in such turbines are very complex. Extensive investigations of supersonic internal flow were performed during several decades by various authors around the Globe. Which led to the development of design and analysis methodologies for such turbines, which are currently used in the industry. However, some important nozzles arrangement parameters are still insufficiently investigated. Some authors demonstrated a significant influence of drilled (round cross-section) convergent-divergent nozzles overlapping on overall turbine efficiency. However, their results were either not formalized in some sort of loss model or formalized in a simplified formula that does not take into account meridional nozzle angle and the diameter where the nozzles are arranged (turbine mean diameter). The meridional nozzles angle and turbine mean diameter affect the shape of the overlapped nozzles area and, thus, have a certain impact on losses caused by overlapping. Besides, the meridional nozzle angle influences the direction of the supersonic flow entrance to the rotor blades which affects the turbine performance even if nozzles have no overlapping. Negligence of these parameters might lead to substantial discrepancies between the predicted and actual performance levels and thus to additional design iterations increasing the turbine development cost.

The paper describes the study of the qualitative and quantitative influence of the mentioned above parameters on aerodynamic losses in drilled convergent-divergent nozzles and overall supersonic turbine performance. Supersonic aerodynamic effects and their influence on turbine performance were determined by employing the state-of-the-art commercial CFD code. Respective mesh sensitivity studies and domains architectures selection considerations are presented. The formalization of the studied nozzle parameters is discussed. The methods used for the determination of the parameters dependencies minimizing the number of CFD calculations are explained. The figures with visualizations of the critical results and numerical values are provided. The obtained loss models are described.

The quantitative loss models obtained as a result of the study, when incorporated into a turbine design and analysis program will enable the opportunity to design and analyze high-efficient supersonic turbines with better accuracy and confidence.

 

Presenting Author: Maksym Burlaka SoftInWay Inc.

Presenting Author Biography: Dr. Burlaka is a Research and Development Manager at SoftInWay Inc. His research interests are in the areas of turbomachinery aero-thermal fluid dynamics, advanced turbine design, transonic and supersonic flows as well as in thermodynamic cycles for airbreathing and rocket propulsion, and power generation with gas turbines, steam, SCO2, and organic fluids, and application of machine learning-based technologies in these areas. He played a substantial role in the development of new turbine design, cycle design, simulation, and optimization technologies at SoftInWay Inc. and at National Technical University “Kharkiv Polytechnic Institute”. Dr. Burlaka has published numerous publications within the area of his scientific interests, including a monograph.

Authors:

Maksym Burlaka SoftInWay Inc.
Leonid Moroz SoftInWay Inc.
Aleksandr Yudin SoftInWay Switzerland GmbH