Effects of tip cavity geometries on the aerothermal performance of the transonic turbine blade with cavity tip

Li, Jun; Du, Kun; Song, Liming

doi:10.1177/0957650915626833

Cited by 14 publications

(5 citation statements)

References 46 publications

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“…With the understanding of the tip leakage flow, there is plenty of experimental and numerical research focusing on the tip geometry. For the cavity tip, Li et al [ 6 ] investigated the effect of cavity depth and the thickness of the squealer rim, and found that the tip leakage flow was enhanced with increasing the thickness of squealer rim. Kang and Less [ 7 ] studied experimentally the effects of squealer rim height-to-span ratio on heat/mass transfer rates, and found that, when the squealer rim height-to-span ratio increased, the averaged heat/mass transfer rate on the cavity floor began to decrease steeply and then decreased slowly.…”

Section: Introductionmentioning

confidence: 99%

Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation

Chen

Yuan

2018

Entropy

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In unshrouded turbine rotors, the tip leakage vortices develop and interact with the passage vortices. Such complex leakage flow causes the major loss in the turbine stage. Due to the complex turbulence characteristics of the tip leakage flow, the widely used Reynolds Averaged Navier–Stokes (RANS) approach may fail to accurately predict the multi-scale turbulent flow and the related loss. In order to effectively improve the turbine efficiency, more insights into the loss mechanism are required. In this work, a Delayed Detached Eddy Simulation (DDES) study is conducted to simulate the flow inside a high pressure turbine blade, with emphasis on the tip region. DDES results are in good agreement with the experiment, and the comparison with RANS results verifies the advantages of DDES in resolving detailed flow structures of leakage flow, and also in capturing the complex turbulence characteristics. The snapshot Proper Orthogonal Decomposition (POD) method is used to extract the dominant flow features. The flow structures and the distribution of turbulent kinetic energy reveal the development of leakage flow and its interaction with the secondary flow. Meanwhile, it is found that the separation bubble (SB) is formed in tip clearance. The strong interactions between tip leakage vortex (TLV) and the up passage vortex (UPV) are the main source of unsteady effects which significantly enhance the turbulence intensity. Based on the DDES results, loss analysis of tip leakage flow is conducted based on entropy generation rates. It is found that the viscous dissipation loss is much stronger than heat transfer loss. The largest local loss occurs in the tip clearance, and the interaction between the leakage vortex and up passage vortex promotes the loss generation. The tip leakage flow vortex weakens the strength of up passage vortex, and loss of up passage flow is reduced. Comparing steady and unsteady effects to flow field, we found that unsteady effects of tip leakage flow have a large influence on flow loss distribution which cannot be ignored. To sum up, the current DDES study about the tip leakage flow provides helpful information about the loss generation mechanism and may guide the design of low-loss blade tip.

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Section: Introductionmentioning

confidence: 99%

Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation

Chen

Yuan

2018

Entropy

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“…Also, because of the relative movement of the casing, part of the OTL flow will get trapped in the middle of the squealer cavity and form a scrapping vortex. In this case, additional suction side corner vortex can be formed in the corner between SS rim and the cavity floor as shown by Pátỳ et al [11], Li et al [12] and Du et al [13].…”

Section: Introductionmentioning

confidence: 82%

Multidisciplinary Optimisation of High Pressure Turbine Blade Tip With Turbine Inlet Capacity and Stage Reaction Constraints

Vincekovic

Qin

Shahpar

2021

Aiaa Aviation 2021 Forum

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This work deals with aerodynamic and aerothermal optimisations of high pressure turbine blade tips where a winglet turbine tip is optimised in terms of both aerodynamic efficiency and integrated heat transfer coefficient. Two constraints were introduced in the optimisation process. In particular, turbine mass flow, defined as a non-dimensional turbine inlet capacity, and stage reaction were constrained to change for up to ±0.5% from the datum values. Turbine inlet capacity and stage reaction constraints were achieved by skewing the rotor blade of turbine stage. Steady RANS simulations with k-𝜔 SST turbulence model were performed for the turbine stage using multi-block fully structured mesh and a mixing plane between the stator and the rotor domain. Gradient based optimiser was used in all the optimisations performed. Aerodynamic optimisation was performed first, with and without the constraints, followed by multidisciplinary optimisation done in three steps. By varying the objective weights to explore the Pareto front, winglet designs with considerable efficiency improvements for only minor increase in heat load were identified, featuring sharp leading edge and suction side overhangs. On the other hand, sharp edges were found to be prone to local aerodynamic heating, highlighting the importance of the aerothermal assessment of this problem.

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“…Simple and optimised squealer tips leakage flow has been described in details by Pátý et al [5] experimentally and numerically. Li et al [6] examined the effect of the squealer rim height and width for a full perimeter squealer. The optimum squealer rim height was found to be 3 times the tip gap.…”

Section: Previous Study On Blade Tip Aerodynamicsmentioning

confidence: 99%

Exploring Topology Optimisation of High Pressure Turbine Blade Tips

Vincekovic

John

Qin

et al. 2020

Volume 2B: Turbomachinery

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This work presents the aerodynamic topology optimisation of high pressure turbine rotor blade tips. Before carrying out the topology optimisation on the blade tip, some initial tip design studies were carried out. The winglet shape was optimised using two different design space setups and parameter limits. The optimum winglet design features the largest overhangs and in the case of unconstrained optimisation proved to have 1.40% greater aerodynamic efficiency. Secondly, a radial basis function based parametrisation was set up to allow the creation of single squealer line using the flat tip blade as a baseline geometry. The optimum case proved to increase efficiency 0.46% compared to the flat tip. After that, a combination of winglet and topology free squealer tips was investigated for topology optimisation. The winglet tip was parametrized as in the winglet only optimisation cases and topology free squealer walls were created using mapping of radial basis function surfaces of different complexities. It is shown that by combining both winglet and novel squealer topology optimisation, better designs of different topologies can be produced.

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Effects of tip cavity geometries on the aerothermal performance of the transonic turbine blade with cavity tip

Cited by 14 publications

References 46 publications

Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation

Entropy Analysis of the Flat Tip Leakage Flow with Delayed Detached Eddy Simulation

Multidisciplinary Optimisation of High Pressure Turbine Blade Tip With Turbine Inlet Capacity and Stage Reaction Constraints

Exploring Topology Optimisation of High Pressure Turbine Blade Tips

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