Studies on a Two-Dimensional Impinging Jet Considering Initial Turbulence : 2nd Report, Static Behaviour of Boundary Layer in the Stagnation Region

Kamoi, Arao; Tanaka, Hideo

doi:10.1299/kikai1938.43.2957

Cited by 4 publications

(2 citation statements)

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“…7, we assume here that the average velocity distribution near the stagnation area can be approximated by theoretical relations for the impinging jet flow treated in past studies. Referring to the method proposed by Kamoi and Tanaka (1977), the flow field was analyzed from the integrated momentum equation, in which the velocity profile in the boundary layer was approximated by a polynomial satisfying the boundary conditions (Schlichting, 1979b). The static pressure at the stagnation point was calculated from the dynamic pressure at the maximum jet velocity shown in Fig.…”

Section: Experimental Results Of Adhesive Forcementioning

confidence: 99%

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A study on the removal of infinitesimal particles on a wall by high-speed air jet―Measurements of adhesive force and particle removal rate―

Katoh

Song

Wakimoto

et al. 2014

JFST

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We investigated the mechanism for the removal of fine particles from a solid wall using a high-speed impinging air jet. In general, it is difficult to remove fine particles of the order of micrometers by the impingement of simple air flow because they strongly adhere to the surface by van der Waals forces and remain immersed in the viscous sublayer. To overcome this, we developed high-speed air jet nozzles with triangular cavities that add strong velocity and pressure fluctuations to the high-speed air flow. The experimental results showed that the cavity nozzle enhances the removal performance for particles larger than 1 μm. The effect of the pressure fluctuation induced in the jet flow on the removal performance is discussed from the experimental results. First, the adhesive force was measured experimentally from the centrifugal force acting on particles with 5-25 μm diameters set on a rotating disk. Based on a simple theoretical consideration regarding the balance of moments acting on a particle, we estimated the effects of hydrodynamic removal forces such as drag, lift, and pressure gradient fluctuation against measured adhesive forces. The theoretical estimation showed that drag plays a major role, and the force of the pressure gradient could be effective for the removal of large particles. The proposed model is able to explain the experimental results indicating that the removal rates for 3-μm-sized particles are improved by the air flow velocity fluctuations generated by the cavity nozzle.

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Section: Experimental Results Of Adhesive Forcementioning

confidence: 99%

“…7. If the pressure distribution in the x-direction is approximated by a Gaussian profile, the free stream velocity can be obtained from Bernoulli's theorem (Kamoi and Tanaka, 1977). The integrated boundary layer equation can be solved numerically by the simple Runge-Kutta method.…”

Section: Experimental Results Of Adhesive Forcementioning

confidence: 99%

A study on the removal of infinitesimal particles on a wall by high-speed air jet―Measurements of adhesive force and particle removal rate―

Katoh

Song

Wakimoto

et al. 2014

JFST

View full text Add to dashboard Cite

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Heat Transfer and Flow Characteristics of an Oblique Turbulent Impinging Jet Within Confined Walls

Ichimiya

1995

Journal of Heat Transfer

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Experiments were conducted to determine the turbulent heat transfer and flow characteristics of an oblique impinging circular jet within closely confined walls using air as a working fluid. The local temperature distribution on the impingement surface was obtained in detail by a thermocamera using a liquid crystal sheet. A correction to the heat flux was evaluated by using the detailed temperature distribution and solving numerically the three-dimensional equation of heat conduction in the heated section. Two-dimensional profiles of the local Nusselt numbers and temperatures changed with jet angle and Reynolds number. These showed a peak shift toward the minor flow region and a plateau of the local heat transfer coefficients in the major flow region. The local velocity and turbulent intensity in the gap between the confined insulated wall and impingement surface were also obtained in detail by a thermal anemometer.

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Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

Ohta

Outa

Tajima

1996

Journal of Turbomachinery

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The blade-passing frequency noise, abbreviated to BPF noise, of a low-specific-speed centrifugal blower is analyzed by separating the frequency response of the transmission passage and the intensity of the noise source. Frequency response has previously been evaluated by the authors using a one-dimensional linear wave model, and the results have agreed well with the experimental response in a practical range of the blower speed. In the present study, the intensity of the noise source is estimated by introducing the quasi-steady model of the blade wake impingement on the scroll surface. The effective location of the noise source is determined by analyzing the cross-correlation between measured data of the blower suction noise and pressure fluctuation on the scroll surface. Then, the surface density distribution of a dipole noise source is determined from pressure fluctuation expressed in terms of quasi-steady dynamic pressure of the traveling blade wake. Finally, the free-field noise level is predicted by integrating the density spectrum of the noise source over the effective source area. The sound pressure level of the blower suction noise is easily predicted by multiplying the free-field noise level by the frequency-response characteristics of the noise transmission passage.

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Studies on a Two-Dimensional Impinging Jet Considering Initial Turbulence : 2nd Report, Static Behaviour of Boundary Layer in the Stagnation Region

Cited by 4 publications

References 0 publications

A study on the removal of infinitesimal particles on a wall by high-speed air jet―Measurements of adhesive force and particle removal rate―

A study on the removal of infinitesimal particles on a wall by high-speed air jet―Measurements of adhesive force and particle removal rate―

Heat Transfer and Flow Characteristics of an Oblique Turbulent Impinging Jet Within Confined Walls

Evaluation and Prediction of Blade-Passing Frequency Noise Generated by a Centrifugal Blower

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