A Novel Method of Coupling the Steam Turbine Exhaust Hood and the Last Stage Blades Using the Non-Linear Harmonic Method

Burton, Zoe; Ingram, Grant; Hogg, Simon

doi:10.1115/gt2013-94184

Cited by 9 publications

(6 citation statements)

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“…The resulting grid size for the exhaust hood alone is roughly 4M nodes, which is in good agreement with recent publications (e.g. Burton et al (2013), Stein et al (2015) etc.) and will therefore not be discussed in more detail here.…”

Section: Figure 3: Mesh Resolutionsupporting

confidence: 91%

“…In recent years it has become popular to not only simulate the flow field in the exhaust hood separately, but rather include the last stage in the simulation to fully grasp the interaction between both (e.g. Stein et al (2015), Burton et al (2013), Li et al (2012) or Polklas (2004)). While these models offer good results with respect to the exhaust performance, a numerical optimisation using these whole exhaust models is still not feasible within the design process.…”

Section: Prior Artmentioning

confidence: 99%

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Combined optimisation of the last stage and diffuser in a steam turbine using meta-models

Musch

Cremanns

Hecker

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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In this study a strategy for a 3D optimisation of the exhaust of a low pressure (LP) steam turbine is presented. The flow domain utilized consists of both the last stage and the exhaust diffuser. The optimisation is done with the help of a hybrid surrogate model for the diffuser flow. In the first part of the paper a numerical model and its validation is presented, which allows for a precise simulation of the diffuser flow including the actual 3D geometry. The second part describes the optimisation procedure and the necessary simplifications applied to this model in order to get a numerical setup that is fast enough to actually perform a design study with roughly 200 design variants within a feasible time. This model is used afterwards to create a surrogate model. Based on this meta model an optimisation is carried out and finally scrutinzed with a flow simulation of the whole exhaust hood.

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Section: Figure 3: Mesh Resolutionsupporting

confidence: 91%

Section: Prior Artmentioning

confidence: 99%

Combined optimisation of the last stage and diffuser in a steam turbine using meta-models

Musch

Cremanns

Hecker

et al. 2017

European Conference on Turbomachinery Fluid Dynamics and Hermodynamics

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show abstract

“…Future publications [33] will show this method can be applied to the exhaust hood and stage system, to enable the nonuniform back pressure generated by the hood geometry to be applied to the rotor outlet. The novel treatment of the rotor-hood interface enables this nonuniformity to be captured when modeling a single blade passage, an effect only previously possible to capture when modeling the full rotor annulus.…”

Section: Numerical and Experimental Methodologiesmentioning

confidence: 98%

A Literature Review of Low Pressure Steam Turbine Exhaust Hood and Diffuser Studies

Burton¹,

Ingram²,

Hogg

2013

Journal of Engineering for Gas Turbines and Power

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This paper summarizes the findings from research studies carried out over the last 30 years, to better understand the flows in steam turbine low pressure exhaust hoods and diffusers. The work aims to highlight the areas where further study is still required. A detailed description of the flow structure is outlined and the influence of the last turbine stage and the hood geometry on loss coefficient is explored. At present, the key challenge faced is numerically modeling the three-dimensional, unsteady, transonic, wet steam exhaust hood flow given the impractically high computational power requirement. Multiple calculation simplifications to reduce the computational demand have been successfully verified with experimental data, but at present there is no 'best-practice' approach to reduce the computational time for routine design exercises. This paper highlights the importance of coupling the exhaust hood to the last stage steam turbine blades to capture the interaction; ensuring the total pressure and swirl angle profiles, along with the tip leakage jet are accurately applied to the diffuser inlet. The nonaxial symmetry of the exhaust hood means it is also important to model the full blade annulus. More studies have emerged modeling the wet steam and unsteady flow effects, but more work is required in this area to fully understand the impact on the flow structure.

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“…al. [25] study compared the mixing plane method of coupling the exhaust hood to the turbine with the non-linear harmonic (NLH) approach. The accurate modelling of the circumferential asymmetry at the exhaust hood inlet with the latter approach was found to yield ∆C p of 0.025 in generous axial length diffusers.…”

Section: Discussionmentioning

confidence: 99%

The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

Burton

Ingram

Hogg

2014

Proceedings of the Institution of Mechanical Engineers, Part A:

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This paper aims to highlight the importance of the accurate computational modelling of both the inlet and outlet exhaust hood boundary conditions. The computations presented are calculated using the public domain LP exhaust diffuser test case proposed by Burton in 2012. The original test case did not include the effect of tip leakage on diffuser flows, this paper describes the inclusion of tip leakage and the results are shown to be in-line with the outputs produced by other authors. The key advance in this paper is that calculations were conducted with a representative condenser pressure gradient caused by the temperature variation inside the condenser tube nest. It is shown that accurately modelling the exit boundary calculation has a large influence on the flow structure and a smaller influence on the pressure recovery inside the exhaust diffuser. This influence is smaller than that seen by other authors when including unsteady effects or accounting for the circumferential non-uniformity of the turbine exit flow but will need to be included in design calculations as diffuser design advances. Nomenclature C p = P 2 −P 1 P T 1 −P 1 Static Pressure Recovery c p

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A Novel Method of Coupling the Steam Turbine Exhaust Hood and the Last Stage Blades Using the Non-Linear Harmonic Method

Cited by 9 publications

References 0 publications

Combined optimisation of the last stage and diffuser in a steam turbine using meta-models

Combined optimisation of the last stage and diffuser in a steam turbine using meta-models

A Literature Review of Low Pressure Steam Turbine Exhaust Hood and Diffuser Studies

The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

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