Experimentelle Prüfung der Analogie zwischen konvektiver Wärme- und Stoffübertragung bei nichtabgelöster Strömung

Presser, K.H.

doi:10.1007/bf00763900

Cited by 24 publications

(5 citation statements)

References 10 publications

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“…It can be concluded that the lower the Reynolds numbers is, the better the analytical solution agrees with the numerical simulations and the experiment. From the similarity between heat and mass transfer , it may be assumed that in the prevailing case the mass transfer can be estimated with Equations and for laminar flow. The authors are aware that the small hole in the specimen influences the local mass transfer but for the present discussion this effect is neglected.…”

Section: Discussionmentioning

confidence: 99%

Effect of gas flow rate on oxidation behaviour of alloy 625 in wet air in the temperature range 900–1000 °C

Huczkowski

Lehnert

Angermann

et al. 2016

Materials & Corrosion

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In many industrial processes, the flow rate of hot gaseous service environments may be in the range of several m/s. In the present paper, the effect of gas flow rate on the high temperature oxidation behaviour of alloy 625 in wet air is presented. The gas velocity was varied from near static conditions to linear gas flow rates up to 6 m/s. The oxidation kinetics were studied by gravimetry during cyclic/discontinuous testing at 900 and 1000 °C. The oxide scales and the subsurface depletion zones formed during exposure were studied by light optical microscopy, scanning electron microscopy with energy dispersive X‐ray analysis and, for selected specimens, by electron backscatter diffraction. It was found that Cr loss due to formation of volatile species is substantially enhanced by high gas flow rates thus significantly influencing the oxidation limited life time of the oxidising component. Within the studied range of flow rates no plateau value was reached, the Cr loss being substantially larger at a flow of 6 m/s than at 0.7 m/s. Additionally, it was found that geometrical factors of the test specimen substantially affected the extent of volatile species formation. Especially the leading edge of the specimen exhibited more extensive Cr loss than the other specimen areas.

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Section: Discussionmentioning

confidence: 99%

Effect of gas flow rate on oxidation behaviour of alloy 625 in wet air in the temperature range 900–1000 °C

Huczkowski

Lehnert

Angermann

et al. 2016

Materials & Corrosion

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“…for naphthalene diffusing in air (--2.47) is different from the Prandtl number of air (= 0.7) the relation between heat and mass transfer is often described by Nu_( Scl Sh -.Pr) 3where the exponent n is assumed to be a constant value between 0.33 and 0.67 (Presser, 1968) depending on flow conditions. It can be exactly calculated for laminar boundary layers and experimentally determined for turbulent flow conditions.…”

Section: Mass (Heat) Transfer Measurement Techniquementioning

confidence: 99%

Highly Resolved Distribution of Heat Transfer for Turbine Leading Edge Film Cooling Including Reynolds Number and Blowing Rate Effects

Jung

Hennecke

1998

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

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The effect of leading edge film cooling on heat transfer was experimentally investigated using the naphthalene sublimation technique. The experiments were performed on a symmetrical model of the leading edge suction side region of a high pressure turbine blade with one row of film cooling holes on each side. Two different lateral inclinations of the injection holes were studied: 0° and 45°. In order to build a data base for the validation and improvement of numerical computations, highly resolved distributions of the heat/mass transfer coefficients were measured. Reynolds numbers (based on hole diameter) were varied from 4000 to 8000 and blowing rate from 0.0 to 1.5. For better interpretation, the results were compared with injection-flow visualizations. Increasing the blowing rate causes more interaction between the jets and the mainstream, which creates higher jet turbulence at the exit of the holes resulting in a higher relative heat transfer. This increase remains constant over quite a long distance dependent on the Reynolds number. Increasing the Reynolds number keeps the jets closer to the wall resulting in higher relative heat transfer. The highly resolved heat/mass transfer distribution shows the influence of the complex flow field in the near hole region on the heat transfer values along the surface.

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“…The wall concentration of naphthalene vapour is given by the ideal-gas law 4with the gas constant of naphthalene RN = 64.84 J/kgK. The saturated vapour pressure data for naphthalene can be calculated from the empirical formula of Presser (1968)…”

Section: Analysis Of Datamentioning

confidence: 99%

The Influence of Rotation on Impingement Cooling

Mattern

Hennecke

1996

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

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The objective of the present work is the experimental investigation of the effects of rotation on the heat transfer due to a single row of circular jets impinging on a curved surface, relevant to turbine blade cooling. The local transfer coefficients were determined by means of the naphthalene sublimation technique using the analogy between heat and mass transfer. Spanwise average transfer coefficients were deduced from the local measurements and are discussed relative to the transfer in a nonrotating system. Results are presented for different stagger angles, jet Reynolds numbers and geometry parameters. The geometry parameters that were varied included the spacing between adjacent jet holes and the distance between the jet hole plate and the impingement surface. It is found that rotation does not improve heat transfer but can reduce it significantly, up to 40% below the transfer coefficient in a nonrotating system. Therefore, the effects of rotation have to be accounted for accurate predictions of the cooling pattern generated by impinging jets.

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Experimentelle Prüfung der Analogie zwischen konvektiver Wärme- und Stoffübertragung bei nichtabgelöster Strömung

Cited by 24 publications

References 10 publications

Effect of gas flow rate on oxidation behaviour of alloy 625 in wet air in the temperature range 900–1000 °C

Effect of gas flow rate on oxidation behaviour of alloy 625 in wet air in the temperature range 900–1000 °C

Highly Resolved Distribution of Heat Transfer for Turbine Leading Edge Film Cooling Including Reynolds Number and Blowing Rate Effects

The Influence of Rotation on Impingement Cooling

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