A Comparative Numerical Study of Aerodynamics and Heat Transfer on Transitional Flow Around a Highly Loaded Turbine Blade With Flow Separation Using RANS, URANS and LES

Schobeiri, Meinhard T.; Nikparto, Ali

doi:10.1115/gt2014-25828

Cited by 16 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Normally, transitional flow is predicted with the traditional two-dimensional models in literature. 11, 22, 23 In this study, a three-dimensional model is used to examine the occurrence of transition for effect of film ejection. Due to the complex structure of jet flow, it is difficult to predict the transitional location.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Numerical study on the effect of different internal angled ribs on the external film cooling performance

Cheng

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

For the blades of gas turbine, the traditional internal ribs have a great impact on the film cooling heat transfer of blade external surface. In this study, SST k-ω turbulence coupled with transition model is adopted to study the effects of angled ribbed passages on external flow and heat transfer characteristics. The detailed flow characteristics were analyzed for two vertically placed flat-plate channels with the blowing ratios of 0.5∼2. The computational model includes a single film hole ( D = 20 mm) with a jet angle of 35°. Four different rib orientations in the secondary flow channels are designed. They are no rib, oblique rib 1 (30° angle from the horizontal line), oblique rib 2 (symmetrical to oblique rib 1), and straight rib. Compared with ribless channel, the average adiabatic film cooling effectiveness of straight rib, Oblique rib 1, Oblique rib 2 are 2.3, 2.2, and 1.9 times higher at different Reynolds numbers, respectively. Taking the film hole as the origin, Oblique rib 2 can greatly improve the overall cooling effectiveness. Oblique rib 1 can improve the cooling effectiveness of the farther downstream wall surface. The comparison of film cooling efficiency, coolant coverage area, flow behavior inside the film hole and that in the downstream, heat transfer and transition behavior for different channels are also analyzed separately. Through the investigations, it helps to understand the effects of internal rib angle on the flow, friction factor and heat transfer outside the film holes.

show abstract

Section: Resultsmentioning

confidence: 99%

“…Schobeiri and Nikparto 11 studied the boundary layer transition and heat transfer outside a highly loaded turbine blade with numerical and experimental approaches. The objective of the research was to identify the heat transfer of the separation region.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the effect of different internal angled ribs on the external film cooling performance

Cheng

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

show abstract

“…This major difference is due to the inaccuracy of the aerodynamic calculation. Detailed investigations by Schobeiri and Nikparto, 29 show that a 5% difference in calculating the aerodynamic properties (pressure, components of the velocity and Reynolds stress tensor) would result in at least 50% difference in HTC and FCE. Accurately predicting the longitudinal and lateral components of the turbulent fluctuations is a prerequisite for correctly calculating the heat transfer behavior.…”

Section: Impact Of Mfr On Fce Experimental and Numerical Results Prementioning

confidence: 99%

Effect of non-axisymmetric contouring on performance and film cooling of a rotating turbine endwall subjected to the secondary air purge: A combined numerical and experimental study

Schobeiri

Rezasoltani

2015

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

Applying a new non-axisymmetric endwall contouring technology introduced by Turbomachinery Performance and Flow Research Laboratory (TPFL) at Texas A&M University to the second rotor row of a three-stage research turbine has shown that for a single rotor row a major turbine efficiency improvement can be achieved. Motivated by these results, numerical and experimental investigations were conducted to determine the effect of non-axisymmetric contouring on the endwall film cooling behavior of a rotating turbine row. To accomplish the film cooling, the endwall of the first rotor row is chosen for the contouring. It is subjected to the secondary air exiting from a large cavity through a circumferential slot that is inclined at 25° and impinges on the contoured hub. Performing Reynolds averaged Navier–Stokes (RANS) simulations by using the boundary conditions from the experiments, aerodynamics, performance, and film cooling effectiveness studies were performed by varying the injection blowing ratio and turbine rotational speed. Performance measurements were carried out within a rotational speed range of 1800–3000 r/min. The corresponding computational fluid dynamic simulations were carried out for four rotational speeds, 2000, 2400, 2600, and 3000 r/min. Comparison of the RANS aerodynamics simulations with experiments reveals noticeable differences. Considering the film cooling effectiveness, major differences between experiment and numerical results were observed and discussed in the paper.

show abstract

“…In aeroengine turbomachinery design, high-fidelity LES is superior to Reynolds-averaged Navier–Stokes (RANS) solvers in capturing flow separation regions. Schobeiri and Nikparto (2014) investigated the development of boundary layers on the suction and pressure surfaces of a highly loaded turbine blade and used the results of RANS and LES for comparison with experimental results, showing that LES predicted more accurately the onset and extent of the separation zone. However, despite the undeniable advantages of LES over unsteady RANS (URANS), the high computational cost of LES in calculating complex flow fields is always a deterrent, and URANS has been shown to be not only an alternative option but also a highly feasible one.…”

Section: Introductionmentioning

confidence: 99%

Multilevel method for predicting flow fields in radial turbines based on sparsity-promoting dynamic mode decomposition

Zheng

Yang

2023

HFF

View full text Add to dashboard Cite

Purpose The purpose of this study is to propose a fast method for predicting flow fields with periodic behavior with verification in the context of a radial turbine to meet the urgent requirement to effectively capture the unsteady flow characteristics in turbomachinery. Aiming at meeting the urgent requirement to effectively capture the unsteady flow characteristics in turbomachinery, a fast method for predicting flow fields with periodic behavior is proposed here, with verification in the context of a radial turbine (RT). Design/methodology/approach Sparsity-promoting dynamic mode decomposition is used to determine the dominant coherent structures of the unsteady flow for mode selection, and for flow-field prediction, the characteristic parameters including amplitude and frequency are predicted using one-dimensional Gaussian fitting with flow rate and two-dimensional triangulation-based cubic interpolation with both flow rate and rotation speed. The flow field can be rebuilt using the predicted characteristic parameters and the chosen model. Findings Under single flow-rate variation conditions, the turbine flow field can be recovered using the first seven modes and fitted amplitude modulus and frequency with less than 5% error in the pressure field and less than 9.7% error in the velocity field. For the operating conditions with concurrent flow-rate and rotation-speed fluctuations, the relative error in the anticipated pressure field is likewise within an acceptable range. Compared to traditional numerical simulations, the method requires a lot less time while maintaining the accuracy of the prediction. Research limitations/implications It would be challenging and interesting work to extend the current method to nonlinear problems. Practical implications The method presented herein provides an effective solution for the fast prediction of unsteady flow fields in the design of turbomachinery. Originality/value A flow prediction method based on sparsity-promoting dynamic mode decomposition was proposed and applied into a RT to predict the flow field under various operating conditions (both rotation speed and flow rate change) with reasonable prediction accuracy. Compared with numerical calculations or experiments, the proposed method can greatly reduce time and resource consumption for flow field visualization at design stage. Most of the physics information of the unsteady flow was maintained by reconstructing the flow modes in the prediction method, which may contribute to a deeper understanding of physical mechanisms.

show abstract

A Comparative Numerical Study of Aerodynamics and Heat Transfer on Transitional Flow Around a Highly Loaded Turbine Blade With Flow Separation Using RANS, URANS and LES

Cited by 16 publications

References 0 publications

Numerical study on the effect of different internal angled ribs on the external film cooling performance

Numerical study on the effect of different internal angled ribs on the external film cooling performance

Effect of non-axisymmetric contouring on performance and film cooling of a rotating turbine endwall subjected to the secondary air purge: A combined numerical and experimental study

Multilevel method for predicting flow fields in radial turbines based on sparsity-promoting dynamic mode decomposition

Contact Info

Product

Resources

About