Investigation into the effect of nozzle shape on the nozzle discharge coefficient and heat and mass transfer characteristics of impinging air jets

Etemoğlu, Akın Burak; Isman, Mustafa Kemal; Can, Muhiddin

doi:10.1007/s00231-010-0666-7

Cited by 15 publications

(6 citation statements)

References 20 publications

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“…The high-velocity air that flows from the nozzles can often cause product degradation if the tensile strength of the paper is low, although higher velocities allow for a higher heat transfer coefficient. It is therefore important to make appropriate adjustments to the jet velocity and the distance of the nozzle from the web surface to obtain the highest quality product with the lowest possible energy consumption (Etemoglu et al 2010).…”

Section: )mentioning

confidence: 99%

“…Obtaining the optimal heat transfer coefficient for the impact area of the air jets involves finding an appropriate shape and size for the nozzles, and suitable values for the distance between the nozzles and the web surface, the velocity and temperature of the air jets, the number of nozzles, and the distance between nozzles. Extensive research in this area has been conducted by Etemoglu et al (2010). Tawfek (1996) determined the heat transfer characteristics of a round jet impinging on an isothermal plate, while Gulati et al (2009) determined the influence of the nozzle shape, the distance between the nozzle and the material, and the Reynolds number on the local heat transfer characteristics.…”

Section: )mentioning

confidence: 99%

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Impact of air jet impingement technology on the strength of tissue paper

Reczulski,

Pospiech,

Troszczyńska

et al. 2024

BioRes

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Impinging air jets can be used to dewater, heat, and dry the web of tissue paper. High velocities of the air jets degrade the paper, and appropriate adjustments to the jet velocity and the distance of the nozzle from the surface of the wet web are crucial to obtain the highest quality product. This work investigated the correlation between the velocity of the air jet and the strength of paper subjected to the impingement method. Papers with an initial moisture content of 20% and various pulp mixes were tested, and the physical properties of papers were explored. After impinging an air jet, different tensile strength limits were obtained in the machine and cross directions. The paper had lower apparent density and higher roughness compared to classical pressing. The dependence of tensile strength and roughness on the fibers composition also was determined. Increasing the amount of eucalyptus fibers in impingement dewatered paper resulted in a decrease in its tensile strength and roughness. The value of elongation before breaking was the highest for softwood papers after the impingement method. The maximum velocity of an air jet that can be used to dewater or dry paper without the risk of damage to the papers was determined.

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Section: )mentioning

confidence: 99%

Section: )mentioning

confidence: 99%

Impact of air jet impingement technology on the strength of tissue paper

Reczulski,

Pospiech,

Troszczyńska

et al. 2024

BioRes

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“…A larger hole with the same z-gap increases heat transfer performance because the z/D ratio gets smaller. In another instance, Etemoglu et al [64] studied the effect of nozzle shape on C d and heat transfer characteristics. As we know now that a sharp-edged orifice performs better than a streamlined nozzle in the z/D range of 3-5, this configuration is commonly used in gas turbines.…”

Section: Jet Orificementioning

confidence: 99%

Opportunities in Jet-Impingement Cooling for Gas-Turbine Engines

Dutta

Singh

2021

Energies

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Impingement heat transfer is considered one of the most effective cooling technologies that yield high localized convective heat transfer coefficients. This paper studies different configurable parameters involved in jet impingement cooling such as, exit orifice shape, crossflow regulation, target surface modification, spent air reuse, impingement channel modification, jet pulsation, and other techniques to understand which of them are critical and how these heat-transfer-enhancement concepts work. The aim of this paper is to excite the thermal sciences community of this efficient cooling technique and instill some thoughts for future innovations. New orifice shapes are becoming feasible due to innovative 3D printing technologies. However, the orifice shape variations show that it is hard to beat a sharp-edged round orifice in heat transfer coefficient, but it comes with a higher pressure drop across the orifice. Any attempt to streamline the hole shape indicated a drop in the Nusselt number, thus giving the designer some control over thermal budgeting of a component. Reduction in crossflow has been attempted with channel modifications. The use of high-porosity conductive foam in the impingement space has shown marked improvement in heat transfer performance. A list of possible research topics based on this discussion is provided in the conclusion.

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“…In order to match the motion feature of point source plume, the jet radius of lawn lamp b and flow height x should meet the requirements of equation (31), 10 and the entrainment coefficient a = 0.09. According to the calculations of equation (31), the following can be identified: b = 30 mm and x = 300 mm…”

Section: Test Measurementsmentioning

confidence: 99%

“…Use thermal plume density r and ambient air density of nonisothermal jets to analyze stress. 31 The upward motion of the thermal plume causes the vertical component of the accelerated velocity to be j = r m À r e r m g = 5Q 6a…”

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confidence: 99%

Interaction mechanism model for a nonisothermal air jet and a buoyant plume

Wang

Shen

et al. 2017

Advances in Mechanical Engineering

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If high-power machines are used and a large number of people are present, a significant amount of heat will be generated, which forms an upward thermal plume. The interaction problem occurs when the cold jet and the thermal plume meet. This article presents the interaction mechanism between a momentum source and a buoyancy source and deduces the interaction parameter b to investigate the effects of parameters such as the power of the source, the air-supply velocity, plume spacing, and nozzle spacing height. Experiments were carried out to investigate the flow field of the air jet affected by the plume and to validate the theoretical work.

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Investigation into the effect of nozzle shape on the nozzle discharge coefficient and heat and mass transfer characteristics of impinging air jets

Cited by 15 publications

References 20 publications

Impact of air jet impingement technology on the strength of tissue paper

Impact of air jet impingement technology on the strength of tissue paper

Opportunities in Jet-Impingement Cooling for Gas-Turbine Engines

Interaction mechanism model for a nonisothermal air jet and a buoyant plume

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