Session: 13-04 - Transients, Unsteadiness and Swirl

Paper Number: 120961

120961 - Study of the Total Temperature Redistribution in the Complex Swirling Flows 

This paper presents the results of a numerical study of the separation of the total temperature occurring  in energetically isolated swirling flows of compressible fluid. The most prominent example of temperature separation is the process of air separation into cold and hot streams in a Ranque-Hilsch vortex tube.

In this work, an object similar in design to the Ranque-Hilsch tube was numerically investigated.  

The in-house SE "Ivchenko-Progress" code SunFlow was used for performing of CFD studies. The SunFlow numerical model is based on the solving of the Reynolds-averaged Navier-Stokes equations written for the cylindrical coordinate system.

The carried-out calculations showed that the separation of total temperature occurs almost equally in non-viscous and viscous gas flows. Which led to the idea that physical viscosity and turbulent vortices are not the main factor causing the phenomenon of separation of total temperature (or enthalpy) of gas. Therefore, further considerations were based on the analysis of the non-viscous flow of a thermodynamically ideal gas.

According to the results of the analysis of the equations of conservation laws written for a non-viscous thermodynamically ideal gas, as well as the results of numerical simulations, the following conclusions were made:

1)The redistribution of total enthalpy (total temperature) occurring in energetically isolated flows of compressible gas is the result of inertia forces.

2)The total temperature difference between hot and cold streams achieved during separation depends on the curvature of the flow streamlines and the value of the tangential velocity.

3)According to the authors, the influence of unsteadiness, diffusion, turbulent shear stresses and turbulent heat transfer on the separation of the total temperature is of a smaller order of magnitude compared to the work of inertia forces.

In addition, the publication provides examples of experimentally obtained redistributions of the total temperature distortions in swirling flows, in particular, in gas turbines, where the flow passing the turbine rows not only rotates relative to the engine axis, but also turns in the vanes and blades flowpath channels around the axes of vanes and blades.

It is shown that the result of radial redistribution of the total temperature distortion in gas turbines is a shift of the maximum temperature to the peripheral sections of the turbines flowpaths, and the redistribution of temperature distortion in the circumferential direction affects the difference of the total temperature at the suction and pressure sides of the turbine blades.

Additionally to the work of inertia forces, in gas turbines, the causes of redistribution of the inlet radial and circumferential total temperature profiles are a number of phenomena such as secondary flows, blade overtip leakages, the presence of blade cooling, interactions with flows in disk cavities, etc.. Estimation of the contribution of each of these components to the process of redistribution of the total temperature distortions in gas turbines will be the subject of further research by the authors.

Presenting Author: Artem Karpenko SE IVCHENKO-PRROGRESS

Presenting Author Biography: Artem Karpenko started working for SE IVCHENKO-PROGRESS aero engine Design Bureau (Ukraine) in 2005 after graduation from Kharkiv Aviation Institute as a mechanical engineer of aircraft engines.
Since then he has been working at SE IVCHENKO-PROGRESS Turbine Research Department as a Design engineer, CFD engineer and Lead engineer.
Artem Karpenko participated in the process of design and modernization of turbines and exhaust systems for different gas turbine engines (D-18T series 3M, AI-222-25, AI-322F, AI-450, D-436-148, etc.)
Artem Karpenko took active part in research works within EU Projects CESAR (FP6) and ESPOSA (FP7). Also he was a leader of the pilot project “Advanced low-cost small turbine” within the AERO-UA project (Horizon 2020).

Authors:

Artem Karpenko SE IVCHENKO-PRROGRESS
Yurii Kukhtin SE IVCHENKO-PROGRESS