Session: 34-07 Turbomachinery Design

Paper Number: 153317

Supersonic Turbines Convergent-Divergent Vaned Nozzles Losses and Deviation Models 

This article continues a series of articles devoted to the development of design and analysis methodology for supersonic turbines to be incorporated into the turbomachine design system.

The earlier published articles in this series are devoted to algorithms for the design and calculation of supersonic convergent-divergent nozzles of two types - drilled [GT2022-83387, GT2023-101760] and vaned [GT2024-125893].

Supersonic nozzles, as part of the turbine stage, are widely used in high-loaded steam and gas turbines, aircraft engines, jet propulsion units, rocket turbo pumps, and others.

The scope of the already published article on convergent-divergent (CDV) supersonic nozzles was limited by the design algorithm and the method for calculating the discharge coefficients of such nozzles. In the current article, we continue presenting the methodology of CDV nozzle losses and flow deviation. The developed methodology accounts for a broad range of operational modes, including design and off-design regimes. The commercial CFD software was the main tool to study flow structure and extract the required information for calculation model development. The methodology includes effects of different geometrical and regime parameters reflecting conditions that CDV nozzles could meet in the practice of high-loaded supersonic turbines of different applications. Proposed nozzle losses and deviation models are based on a detailed study of supersonic flow physics into channels of different geometry and operation conditions. The proposed variant of the losses model includes two constituents- the design point losses model and the off-design correction factor. The design mode losses model is presented as a sum of profile losses and secondary (end walls) losses. Profile losses are a function of several parameters, varying in broad ranges such as – design pressure ratio, fluid-specific heat ratio, nozzle axis angle, Reynolds number and walls roughness, trailing edge shape (cylindrical vs. cut-ff) and thickness, distance from trailing edge (TE) and effect of shock waves from downstream located blades leading edge. The secondary losses are a function of the nozzle's relative height. The off-design operation is accounted for by the correction factor to the design mode losses, which is a complex function of nozzle design pressure ratio, fluid-specific heat ratio, and regime parameter. The physics of supersonic flow at design and off-design modes is illustrated by CFD results to support some assumptions used in loss and deviation model development.

The results presented in this article, together with earlier published [GT2024-125893] have completed the development of design and computational models for CDV nozzles, which include discharge coefficients, losses, and deviation. The design algorithm and models were incorporated into the turbomachine design system. The generated by this system supersonic turbine stages were verified in CFD.

 The validation showed a good match in terms of losses in the nozzles in different modes of operation. The developed mathematical model of CDV nozzles is recommended for use in the design system of turbomachines for supersonic stages.

Presenting Author: Leonid Moroz SoftInWay, Inc.

Presenting Author Biography: Dr. Leonid Moroz is President and CEO of SoftInWay, Inc., a global engineering company specializing in the development of efficient propulsion and energy conversion systems.

Dr. Moroz graduated from Kharkiv Polytechnic University, Kharkiv, Ukraine in 1982. For the first ten years of his career, he held various engineering and management positions at NPO TURBOATOM, in Kharkiv, Ukraine. During that time, he focused on designing of gas (with power up to 115MW) and steam (with power up to 1000MW) turbines.

In 1999, he founded SoftInWay, Inc. and has been leading the company activities in the areas of aerospace and defense for more than 25 years. SoftInWay Inc. delivers time and cost savings for turbomachinery, propulsion, and energy systems through expert engineering services and the innovative software platform AxSTREAM.

His focus includes responsibility for enabling overall product strategy, roadmap, and plans, and linking together development and business units. He leads and oversees advanced technology projects and prototyping of innovations in product development for potential commercialization. He manages sponsored research activities, and externally funded R&D, and promotes cross-company technology sharing and collaborative research. SoftInWay, Inc. has developed and marketed the software platform AxSTREAM; a powerful integrated software platform for designing, analyzing, and optimizing turbomachinery and thermal fluid systems found in energy and propulsion technology. Users of the AxSTREAM platform include Rolls-Royce, RTX, Boeing, and Siemens.

One of the development goals of Dr. Moroz’s team is implementing a holistic approach as a key driver of developing next-generation propulsion for hypersonic and space applications. Under Dr. Moroz’s leadership, SoftInWay is actively working with NASA and the US Air Force and has won multiple Phase 1 and Phase 2 SBIR awards.

Authors:

Leonid Moroz SoftInWay, Inc.
Maksym Burlaka SoftInWay, Inc.
Boris Frolov SoftInWay Switzerland GmbH
Tetiana Dyzenko SoftInWay Switzerland GmbH