Three-Dimensional Navier-Stokes Analysis of Tip Clearance Flow in Linear Turbine Cascades

AIAA Journal ◽  
1993 ◽  
Vol 31 (11) ◽  
pp. 2068-2074 ◽  
Author(s):  
Jong-Shang Liu ◽  
Riccardo Bozzola
Keyword(s):  
Three Dimensional ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Turbine Cascades

Numerical Study of the Tip Clearance Flow Development in a Propulsion Pump Stage

1996 ◽  
Author(s):  
Yu-Tai Lee ◽  
Chunill Hah ◽  
James Loellbach
Keyword(s):  
Vortex Structure ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Navier Stokes ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
High Reynolds

This paper summarizes a numerical investigation of the fundamental structure of the rotor tip-clearance vortex and its interaction with a passage trailing-edge vortex in a single-stage stator-rotor pump. The flow field of a highly-loaded rotor measured in a high Reynolds number pump facility (HIREP) is used for comparison. The numerical solution was obtained by solving the three-dimensional Reynolds averaged Navier-Stokes equations. The calculated results are visualized in order to understand the details of the tip-vortex structure. The study shows that the tip geometry should be accurately represented to predict the tip-vortex structure correctly.

A Numerical Modeling of Endwall and Tip-Clearance Flow of an Isolated Compressor Rotor

1986 ◽  
Vol 108 (1) ◽  
pp. 15-21 ◽  
Author(s):  
C. Hah
Keyword(s):  
Three Dimensional ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Tip Clearance Flow ◽  
Generalized Coordinates ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Flow Phenomena ◽  
Entire Flow

The current study is aimed at developing and appraising a numerical method for the development of endwall boundary layers through tip-clearances and their effect on the performance of an isolated compressor rotor. The Reynolds-averaged Navier-Stokes equation is solved for the entire flow field in elliptic form. The relative flow is computed on the generalized coordinates fixed on the rotor. Comparison between the numerical results and experimental data indicates that the complex three-dimensional viscous flow phenomena inside the tip region are properly predicted.

Method for Non-Dimensional Tip Leakage Flow Characterization in Radial Turbines

2018 ◽  
Author(s):  
José Ramón Serrano ◽  
Roberto Navarro ◽  
Luis Miguel García-Cuevas ◽  
Lukas Benjamin Inhestern
Keyword(s):  
Suction Side ◽  
Tip Clearance ◽  
Navier Stokes ◽  
The Novel ◽  
Tip Leakage Flow ◽  
Navier Stokes Equation ◽  
Tip Clearance Flow ◽  
Tip Leakage ◽  
Wide Range ◽  
Clearance Flow

Tip leakage loss characterization and modeling plays an important role in small size radial turbine research. The momentum of the flow passing through the tip gap is highly related with the tip leakage losses. The ratio of fluid momentum driven by the pressure gradient between suction side and pressure side and the fluid momentum caused by the shroud friction has been widely used to analyze and to compare different sized tip clearances. However, the commonly used number for building this momentum ratio lacks some variables, as the blade tip geometry data and the viscosity of the used fluid. To allow the comparison between different sized turbocharger turbine tip gaps, work has been put into finding a consistent characterization of radial tip clearance flow. Therefore, a non-dimensional number has been derived from the Navier Stokes Equation. This number can be calculated like the original ratio over the chord length. Using the results of wide range CFD data, the novel tip leakage number has been compared with the traditional and widely used ratio. Furthermore, the novel tip leakage number can be separated into three different non-dimensional factors. First, a factor dependent on the radial dimensions of the tip gap has been found. Second, a factor defined by the viscosity, the blade loading, and the tip width has been identified. Finally, a factor that defines the coupling between both flow phenomena. These factors can further be used to filter the tip gap flow, obtained by CFD, with the influence of friction driven and pressure driven momentum flow.

Effect of tip clearance size on the performance of a low-reaction transonic axial compressor rotor

2019 ◽  
Vol 234 (2) ◽  
pp. 127-142
Author(s):  
Wei Zhu ◽  
Songtao Wang ◽  
Longxin Zhang ◽  
Jun Ding ◽  
Zhongqi Wang
Keyword(s):  
Numerical Simulations ◽  
Dynamic Balance ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Stall Margin ◽  
Tip Clearance Flow ◽  
Compressor Rotor ◽  
Clearance Flow ◽  
Flow Phenomena

This study aimed to enhance the understanding of flow phenomena in low-reaction aspirated compressors. Three-dimensional, multi-passage steady and unsteady numerical simulations are performed to investigate the performance sensitivity to tip clearance variation on the first-stage rotor of a multistage low-reaction aspirated compressor. Three kinds of tip clearance sizes including 1.0τ, 2.0τ and 3.0τ are modeled, in which 1.0τ corresponds to the designed tip clearance size of 0.2 mm. The steady numerical simulations show that the overall performance of the rotor moves toward lower mass flow rate when the tip clearance size is increased. Moreover, energy losses, efficiency reduction and stall margin decrease are also observed with increasing tip clearance size. This can be mostly attributed to the damaging impact of intense tip clearance flow. For unsteady simulation, the result shows periodical oscillation of the tip leakage vortex and a “two-passage periodic structure” in the tip region at the near-stall point. The occurrence of the periodical oscillation is due to the severe interaction between the tip clearance flow and the shock wave. However, the rotor operating state is still stable at this working point because a dynamic balance is established between the tip clearance flow and incoming flow.

Leakage Effects in the Rotor Tip-Clearance Region of a Multistage Axial Compressor: Part 2 — Numerical Modelling

1998 ◽  
Author(s):  
E. S. Politis ◽  
K. C. Giannakoglou ◽  
K. D. Papailiou
Keyword(s):  
Axial Compressor ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Computational Domain ◽  
Loose Coupling ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Flow Effects ◽  
Multistage Axial Compressor ◽  
Asme Paper

Innovative measurements of tip-clearance flow for the 3rd stage rotor embedded in a four stage Low-Speed Research Compressor are presented in the companion ASME paper. Here, in Part 2, the rotor flow is numerically simulated through a Navier-Stokes solver implementing the k-ε turbulence model. The 3rd stage rows are considered as discrete parts of the same computational domain and the flow in each one of them is treated as steady in the corresponding system of reference. An iterative, though loose, coupling between the rotor exit and the stator inlet is established by artificially increasing the inter-row distance. To model tip-clearance flow effects with sufficient accuracy, a two-block grid system per row is used. Comparisons with measurements published in Part 1 for the average flow quantities at the exit of both rows are presented. Row patterns close to the rotor tip-clearance region are illustrated.

Three-Dimensional Flowfields Inside a Transonic Compressor With Swept Blades

1991 ◽  
Vol 113 (2) ◽  
pp. 241-250 ◽  
Author(s):  
C. Hah ◽  
A. J. Wennerstrom
Keyword(s):  
Turbulence Modeling ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Tip Clearance Flow ◽  
Transonic Compressor ◽  
Improved Performance

The concept of swept blades for a transonic or supersonic compressor was reconsidered by Wennerstrom in the early 1980s. Several transonic rotors designed with swept blades have shown very good aerodynamic efficiency. The improved performance of the rotor is believed to be due to reduced shock strength near the shroud and better distribution of secondary flows. A three-dimensional flowfield inside a transonic rotor with swept blades is analyzed in detail experimentally and numerically. A Reynolds-averaged Navier–Stokes equation is solved for the flow inside the rotor. The numerical solution is based on a high-order upwinding relaxation scheme, and a two-equation turbulence model with a low Reynolds number modification is used for the turbulence modeling. To predict flows near the shroud properly, the tip-clearance flow also must be properly calculated. The numerical results at three different operating conditions agree well with the available experimental data and reveal various interesting aspects of shock structure inside the rotor.

A Comparison Between the Design Point and Near-Stall Performance of an Axial Compressor

1990 ◽  
Vol 112 (1) ◽  
pp. 109-115 ◽  
Author(s):  
N. M. McDougall
Keyword(s):  
Rotor Blade ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Design Point ◽  
Blade Row ◽  
Clearance Flow ◽  
Stator Blade

Detailed measurements have been made within an axial compressor operating both at design point and near stall. Rotor tip clearance was found to control the performance of the machine by influencing the flow within the rotor blade passages. This was not found to be the case in the stator blade row, where hub clearance was introduced beneath the blade tips. Although the passage flow was observed to be altered dramatically, no significant changes were apparent in the overall pressure rise or stall point. Small tip clearances in the rotor blade row resulted in the formation of corner separations at the hub, where the blade loading was highest. More representative clearances resulted in blockage at the tip due to the increased tip clearance flow. The effects that have been observed emphasize both the three-dimensional nature of the flow within compressor blade passages, and the importance of the flow in the endwall regions in determining the overall compressor performance.

Physics of Tip Clearance Flow in Turbomachinery (Keynote Paper)

2002 ◽  
Author(s):  
Masahiro Inoue ◽  
Masato Furukawa
Keyword(s):  
Flow Field ◽  
Physical Interpretation ◽  
Vortex Core ◽  
Vortical Structure ◽  
Three Dimensional ◽  
Axial Flow ◽  
Tip Clearance ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
Flow Phenomena

In a recent advanced aerodynamic design of turbomachinery, the physical interpretation of three-dimensional flow field obtained by a numerical simulation is important for iterative modifications of the blade or impeller geometry. This paper describes an approach to the physical interpretation of the tip clearance flow in turbomachinery. First, typical flow phenomena of the tip clearance flow are outlined for axial and radial compressors, pumps and turbines to help comprehensive understanding of the tip clearance flow. Then, a vortex-core identification method which enables to extract the vortical structure from the complicated flow field is introduced, since elucidation of the vortical structure is essential to the physical interpretation of the tip clearance flow. By use of the vortex-core identification, some interesting phenomena of the tip clearance flows are interpreted, especially focussing on axial flow compressors.

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