Experimental investigation of the heat exchange in separation zones of a turbulent boundary layer ahead of a step

Luzhanskii, B. E.; Solntsev, V. P.

doi:10.1007/bf00853992

Cited by 2 publications

(3 citation statements)

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“…Such a decreasing trend is reversed by a sharp peak immediately ahead of the step at x/I-1 --0.5. The same observation was reported earlier by Luzhanskiy and Solntev (1971). Although the actual cause of this phenomenon is somewhat unknown and a subject to further study, the elevated turbulence level associated with a vortex or several vortices, embedded in the lower corner ahead of the step appears to be a main reason.…”

Section: Heat Transfer On a Misaligned Gap Without Leakagesupporting

confidence: 85%

“…In contrast, the heat transfer downstream of a cavity is dependent on the cavity size and is very similar to the characteristics of a newly developing boundary layer. Luzhanskiy and Solntev (1971) have reported heat transfer in the separated flow zone ahead of a forward facing step. They measured local enhancements of up to 1.5 at the separation region of the step corner.…”

Section: Figure 2 Misaligned Component To Component Interfacesmentioning

confidence: 99%

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Measurements of Heat Transfer Characteristics of Gap Leakage Around a Misaligned Component Interface

Chyu

Hsing

Bunker

1998

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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In an attempt to understand the effects of leakage through a component-to-component interface on the turbine end wall heat transfer, this paper describes an experimental efforts on examining the detailed heat transfer characteristics near a leaking gap. Geometric misalignment around the gap is modeled by either a forward-facing step or a backward-facing step. Heat transfer measurement here uses a temperature-sensitive fluorescent imaging of a thermographic phosphor (TGP). The TGP technique reveals detailed distribution of local heat transfer coefficient and adiabatic wall temperature in the vicinity of the leakage. The results suggest that, for a given leakage-to-mainstream mass flow ratio, the adiabatic wall temperature closes to the level of leakage temperature and is relatively insensitive to the nature of misalignment. On the outer hand, however, the value of heat transfer coefficient varies strongly with misalignment and streamwise location relative to the gap. Overall, the leakage thickens the approaching boundary layer and significantly extends the length of reattachment downstream compared to the corresponding cases without leakage. To further qualify the TGP technique, which is relatively new for transient measurement of local heat transfer, an analysis toward its efficacy in resolving complex convective system is developed in this study. One of the main advantages that TGP inherits is its capability of determining both heat transfer coefficient and reference temperature based on a single test. Other methods, such as the transient liquid crystal technique, generally require separate tests each with different thermal conditions.

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Section: Heat Transfer On a Misaligned Gap Without Leakagesupporting

confidence: 85%

Section: Figure 2 Misaligned Component To Component Interfacesmentioning

confidence: 99%

Measurements of Heat Transfer Characteristics of Gap Leakage Around a Misaligned Component Interface

Chyu

Hsing

Bunker

1998

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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show abstract

“…All have come to the same general conclusions regarding the effect on local heat transfer, showing enhancement factors of as much as 2 to 3 occurring within the entry contraction region, as well as at the reattachment region some six step heights downstream of a step. Heat transfer in the separated flow zone ahead of a forward facing step has been reported by Luzhanskiy and Solntsev18. In general, the various studies have used very thin incoming boundary layers prior to the step, so that the results are indicative of step heights many times the size of the momentum thickness, which is the case within blade tip regions.…”

Section: Blade Tip Heat Transfermentioning

confidence: 96%

A Review of Turbine Blade Tip Heat Transfer

Bunker

2001

Annals of the New York Academy of Sciences

148

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This paper presents a review of the publicly available knowledge base concerning turbine blade tip heat transfer, from the early fundamental research which laid the foundations of our knowledge, to current experimental and numerical studies utilizing engine‐scaled blade cascades and turbine rigs. Focus is placed on high‐pressure, high‐temperature axial‐turbine blade tips, which are prevalent in the majority of today's aircraft engines and power generating turbines. The state of our current understanding of turbine blade tip heat transfer is in the transitional phase between fundamentals supported by engine‐based experience, and the ability to a priori correctly predict and efficiently design blade tips for engine service.

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Experimental investigation of the heat exchange in separation zones of a turbulent boundary layer ahead of a step

Cited by 2 publications

References 1 publication

Measurements of Heat Transfer Characteristics of Gap Leakage Around a Misaligned Component Interface

Measurements of Heat Transfer Characteristics of Gap Leakage Around a Misaligned Component Interface

A Review of Turbine Blade Tip Heat Transfer

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