Influence of Sealing Air Mass Flow on the Velocity Distribution In and Inside the Rim Seal of the Upstream Cavity of a 1.5-Stage Turbine

Bohn, Dieter; Decker, Achim; Ma, Hongwei; Wolff, Michael W.

doi:10.1115/gt2003-38459

Cited by 29 publications

(12 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The above studies were concurrent with, but independent of, the ICAS-GT and ICAS-GT2 research programmes reported by Smout et al [41]. Smout et al stated that fast response pressure measurements on a turbine rim sealing rig designed by Bohn et al [42] at RWTH Aachen University had shown low frequency unsteadiness unrelated to blade passing. The presence of large scale unsteady structures was suggested as a possible cause of discrepancies between measurements and URANS modelling for a 22.5 o periodic sector.…”

Section: Axial Rim Sealsmentioning

confidence: 68%

Flow mechanisms in axial turbine rim sealing

Chew

Gao

Palermo

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

This paper presents a review of research on turbine rim sealing with emphasis placed on the underlying flow physics and modelling capability. Rim seal flows play a crucial role in controlling engine disc temperatures but represent a loss from the main engine power cycle and are associated with spoiling losses in the turbine. Elementary models that rely on empirical validation and are currently used in design do not account for some of the known flow mechanisms, and prediction of sealing performance with computational fluid dynamics (CFD) has proved challenging. CFD and experimental studies have indicated important unsteady flow effects that explain some of the differences identified in comparing predicted and measure sealing effectiveness. This review reveals some consistency of investigations across a range of configurations, with inertial waves in the rotating flow apparently interacting with other flow mechanisms which include vane, blade and seal flow interactions, disc pumping and cavity flows, shear layer and other instabilities, and turbulent mixing.

show abstract

Section: Axial Rim Sealsmentioning

confidence: 68%

Flow mechanisms in axial turbine rim sealing

Chew

Gao

Palermo

2018

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

show abstract

“…However this finding was later questioned by Hills et al 14 Experiments conducted by Bohn et al 15 with a shrouded stator and unshrouded rotor showed an increase in sealing efficiency when blades were introduced; the opposite effect was shown for the case with two unshrouded discs. Unsteady LDV measurements made by Bohn et al 16 in a 1.5 stage turbine rig then showed ingestion intensified as the rotor blades passed through the stator wake.…”

Section: Review Of Relevant Papersmentioning

confidence: 95%

“…The so-called effectiveness equations express ε, the sealing effectiveness, in terms of Φ0, the sealing parameter, which is defined as b Ω U Re G π 2 C Φ c w,0 0    (16) where U is the bulk-mean velocity through the rim-seal clearance and the other symbols are defined in the Appendix 1.…”

Section: Equations For Orifice Modelmentioning

confidence: 99%

Experimental measurements of hot gas ingestion through turbine rim seals at off-design conditions

Scobie

Sangan

Owen

et al. 2014

Proceedings of the Institution of Mechanical Engineers, Part A:

View full text Add to dashboard Cite

This paper describes results obtained from an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. The experimental rig included 32 nozzle guide vanes and 41 symmetrical turbine blades, and the paper presents measurements of ε (the sealing effectiveness) for single-and double-clearance seals for both over-speed (where the blades rotate faster than at the design point) and under-speed conditions. The design flow coefficient was CF = 0.538, and tests were conducted for 0 < CF < 0.9, which is larger than the range experienced in engines. The measured values of ε were correlated by the 'effectiveness equations' for rotationally-induced (RI) and externallyinduced (EI) ingress.The correlated effectiveness curves were used to determine Φmin' (the value of the sealing flow parameter when ε = 0.95), and the variation of Φmin' with CF was in mainly good agreement with the theoretical curve for CI (combined ingress), which covered the transition from RI to EI ingress. Departure of the measured values of Φmin' from the CI curve occurred at very low values of CF for all the seals tested; this was attributed to the effects of separation of the mainstream flow over the turbine blades at large 'deviation angles' between the flow and the blades.The measurements are expected to be qualitatively similar to but quantitatively different from those experienced in engines. KeywordsGas turbines, air cooling, industrial turbomachinery RI min, , w CI min, , w RI min, CI min,

show abstract

“…The boundary conditions on the rim seal in the main gas path are not only affected by the upstream vanes but also by the interaction of the vane and blade pressure fields. Unsteady flow field measurements, performed by Bohn et al [8] in the outer portion of the rim cavity for a simple axial seal, showed the strong influence of the passing rotor on ingestion. The potential field of the passing rotor interacted with the vane wake flow and caused more ingestion than when the passing rotor interacted with the vane core flow.…”

Section: Introductionmentioning

confidence: 98%

Effects of Purge Flow Configuration on Sealing Effectiveness in a Rotor–Stator Cavity

Clark

Barringer

Johnson

et al. 2018

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

Secondary air is bled from the compressor in a gas turbine engine to cool turbine components and seal the cavities between stages. Unsealed cavities can lead to hot gas ingestion, which can degrade critical components or, in extreme cases, can be catastrophic to engines. For this study, a 1.5 stage turbine with an engine-realistic rim seal was operated at an engine-relevant axial Reynolds number, rotational Reynolds number, and Mach number. Purge flow was introduced into the interstage cavity through distinct purge holes for two different configurations. This paper compares the two configurations over a range of purge flow rates. Sealing effectiveness measurements, deduced from the use of CO2 as a flow tracer, indicated that the sealing characteristics were improved by increasing the number of uniformly distributed purge holes and improved by increasing levels of purge flow. For the larger number of purge holes, a fully sealed cavity was possible, while for the smaller number of purge holes, a fully sealed cavity was not possible. For this representative cavity model, sealing effectiveness measurements were compared with a well-accepted orifice model derived from simplified cavity models. Sealing effectiveness levels at some locations within the cavity were well-predicted by the orifice model, but due to the complexity of the realistic rim seal and the purge flow delivery, the effectiveness levels at other locations were not well-predicted.

show abstract

Influence of Sealing Air Mass Flow on the Velocity Distribution In and Inside the Rim Seal of the Upstream Cavity of a 1.5-Stage Turbine

Cited by 29 publications

References 3 publications

Flow mechanisms in axial turbine rim sealing

Flow mechanisms in axial turbine rim sealing

Experimental measurements of hot gas ingestion through turbine rim seals at off-design conditions

Effects of Purge Flow Configuration on Sealing Effectiveness in a Rotor–Stator Cavity

Contact Info

Product

Resources

About