Controlling of workpiece distortion by quenching in flexible Fluid Jet Fields∗

Schüttenberg, S.; Krause, F.; Hunkel, M.; Zoch, Hans‐Werner; Fritsching, Udo

doi:10.3139/105.100424

Cited by 8 publications

(2 citation statements)

References 2 publications

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“…In investigations concerning the submerged liquid jet quenching of shafts and plane surfaces with water jets in a water bath, several combinations of the nozzle parameters were investigated concerning their influence on the vapor film formation (Schuettenberg et al, 2006(Schuettenberg et al, , 2009(Schuettenberg et al, , 2007Stark et al, 2012). Here, the smallest investigated nozzle diameter combined with the lowest nozzle outlet velocity Figure 3) still lead to an instantaneous collapse of the vapor film in the stagnation region as described above for free-surface jet cooling applications.…”

Section: Resultsmentioning

confidence: 97%

Simulation of the impinging liquid jet cooling process of a flat plate

Stark

Fritsching

2015

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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Purpose -The purpose of this paper is to develop a numerical model to simulate the flow field as well as the conjugate heat transfer during unsteady cooling of a flat plate with a single submerged water jet. At wall temperatures above the liquid boiling point, the vapor formation process and the interaction of the vapor phase with the developing jet-flow field are included. Design/methodology/approach -The time-dependent flow and temperature distribution during all occurring boiling phases as well as the local and temporal distribution of the heat transfer coefficient on a flat plate can be simulated. Findings -The influence of the liquid jet flow rate (10,800 ¼ Re_d ¼ 32,400) and the nozzle distance to the plate (4 ¼ H/d ¼ 20) on the transient cooling process are analyzed. This includes the time-dependant positions of the transition regions between the boiling phases on the plate as well as the temperatures at these transition regions. Additionally, the local heat transfer rates are a direct result of the unsteady cooling simulation. Originality/value -A single model approach is developed and utilized to simulate the unsteady cooling process of a flat plate with an impinging water jet including all occurring boiling phases.bubble d diameter e energy liq liquid m mass p, q phase indicator ref reference sat saturation sub subcooling sup wall superheat vap vapor 153 Liquid jet cooling process of a flat plate Introduction Boiling phases and boiling heat transferThe heat transfer from a heated specimen to a liquid at wall temperatures above the boiling temperature of the liquid (T wall 4T sat ) is significantly influenced by boiling phenomena and vapor formation processes. At high surface temperatures a vapor film may be formed, separating the hot solid body from the surrounding liquid. During this film boiling phase, the low conductivity of the vapor phase causes low heat transfer rates. When the wall temperature decreases below the "Leidenfrost-point" the vapor film collapses and the surface partially rewets. This transition point is in coincidence with a local minimum in the heat flux distribution from the surface. Here, the partial contact between the hot wall and the cooling liquid as well as the considerable amount of generated vapor intensifies the heat transfer rates in this nucleate or transition boiling regimes. The convective heat transfer is intensified through the increased movement through bubble formation and detaching processes and an additional amount of energy proportional to the evaporation rate is removed through the latent heat (Kandlikar, 1999;Auracher and Marquardt, 2004;Liščić, 2009). The maximum heat transfer rate is achieved at the critical heat flux (CHF) or departure from nucleation boiling point. For wall temperatures below the saturation temperature of the liquid, evaporation stops and heat transfer can be described based on the mechanisms for convective single-phase flows. The heat transfer rate vs surface temperature in this transient cooling process is described by the Nukiyama-curve ...

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Section: Resultsmentioning

confidence: 97%

Simulation of the impinging liquid jet cooling process of a flat plate

Stark

Fritsching

2015

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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“…A qualitative distribution of the heat transfer with a periodic change of higher and lower intensities on the outer surface and lower and constant values of the HTC at all other surfaces was chosen as it was originally developed for distortion compensation at smaller rings in gas nozzle field [6], Figure 4. In the stagnation zones at regions with higher heat transfer coefficients, the determined time-dependent heat transfer coefficients during jet quenching in water are used in the numerical simulation (Chapter 4.3).…”

Section: Numerical Simulation Of the Distortion Potential Of Large Ringsmentioning

confidence: 99%

Process integrated distortion compensation of large bearing rings

Stark¹,

Fritsching

Hunkel

et al. 2012

Materialwissenschaft Werkst

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Bearing rings (d F 1000 mm, material: 42CrMo4) may be quenched directly after the hot rolling process with the use of adapted jet fields. Specific asymmetric cooling conditions for controlled heat treatment processes shall be utilized for distortion compensation. The feasibility of liquid quenching techniques (water jet cooling a) in water b) in ambient air and c) spray cooling) is investigated experimentally concerning the achievable cooling curves of the ring specimen and the resulting heat transfer coefficients on its surface. The influence of the distribution of the quenching intensities around the ring's circumference on the achievable distortion compensation behaviour is investigated both experimentally in a jet nozzle field and through numerical simulations.Keywords: Ring rolling / jet quenching / spray quenching / heat transfer coefficient / process integrated quenching / Wälzlagerringe (d F 1000 mm, Werkstoff: 42CrMo4) sollen direkt nach dem Ringwalzprozess in flexiblen Flüssigkeitsdüsenfeldern in einer geeigneten Weise abgeschreckt werden, so dass eine asymmetrische Verteilung der Abschreckintensitäten eine zielgerichtete Kompensation vorliegender Bauteilverzüge bereits während des Wärmebehandlungsprozesses ermöglicht. Verschiedene Abschreckverfahren mit flüssigen Abschreckmedien (Jet-, Spritz-und Spraykühlung mit Wasser) werden experimentell auf ihre diesbezügliche Anwendbarkeit, insbesondere hinsichtlich der erzielbaren Abkühlverläufe und der damit verbundenen lokalen Wärmeübergänge, untersucht. Die Auswirkung der Verteilung der Abschreckintensitäten um den Umfang des Ringes auf das erreichbare Kompensationspotenzial zur gezielten Verzugsminimierung wird ebenfalls experimentell ermittelt und mit Werkstoffsimulationen verglichen.

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Gas-Jet Quenching

Stratton

2008

Journal of ASTM International

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It has been suggested that gas quenching of a single component or single layers of components that have been heated in vacuum or conventional atmosphere furnaces can achieve higher quenching rates than those possible with conventional multi-component gas quenching. Such treatments could meet the need for a clean, non-toxic quenching medium that leaves no residues to be removed after processing. The processing of single components gives the operator complete control of quenching intensity, both locally and overall. Moreover, the quenching rate may be changed during the quenching cycle. Extensive computational fluid dynamics modeling of cooling using nitrogen jets has shown that an array of high velocity gas jets close to the surface of a part can cool it at a speed similar to oil. The optimum conditions were: an approximately uniform nozzle field with the jets four to eight times their own diameter apart, at a distance from the part to be quenched of a quarter of the diameter of the jets; and a jet velocity of 100 m/s (224 mph). When these optimized conditions were applied to an idealized gear form, the model suggested that it would be fully hardened if a nitrogen/hydrogen mixture was used.Calculation indicated that in this type of nozzle field, the part would float between the arrays of jets, eliminating the need to fix it. The model was validated using a physical test rig and was found to give results very close to reality, so it could be used to predict cooling behavior. The test rig was also used to quench carburized gear blanks. The hardness profiles produced by quenching in different gas mixtures were compared to those from oil quenched samples, the results confirming the original modeling.

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Controlling of workpiece distortion by quenching in flexible Fluid Jet Fields∗

Cited by 8 publications

References 2 publications

Simulation of the impinging liquid jet cooling process of a flat plate

Simulation of the impinging liquid jet cooling process of a flat plate

Process integrated distortion compensation of large bearing rings

Gas-Jet Quenching

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