The Flow around an Oscillating Sphere : 2nd Report, The Measurement of Unsteady Drag

Urakawa, Takuro; Takahashi, Koji

doi:10.1299/jsme1958.26.978

Cited by 1 publication

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“…According to previous works on the bluff bodies such as a circular cylinder and sphere oscillating in liquids at rest,5–9 the equation with the Reynolds number gives the relationships between the drag or added mass coefficients and oscillating parameters and physical properties of liquids. The Reynolds number characterizing the flow in an agitated vessel, ie the impeller Reynolds number, Re m , is defined with the characteristic length of the diameter of the impeller, D i , and the characteristic velocity of the product of D i and rotation rate of the impeller, N r , by the following equation: where ν is the kinematic viscosity of liquid.…”

Section: Resultsmentioning

confidence: 99%

Power characteristics of unsteadily forward–reverse rotating impellers in an unbaffled aerated agitated vessel

Yoshida

Ito

Yamagiwa

et al. 2001

J of Chemical Tech & Biotech

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Power characteristics of an unbaf¯ed aerated agitated vessel with unsteadily forwardreverse rotating impellers, ie a new type of gas±liquid agitator named`AJITER', treating viscous Newtonian liquids were studied experimentally. Measurements were ®rst made on the agitation torque, ie the torque on the drive shaft on which forward±reverse rotating impellers with four deltatype blades were attached, and the data obtained were analyzed by ®tting them to an equation consisting of two terms with respect to the resistance of the¯uid, one due to viscous drag and the other due to added moment of inertia. The effects of operating conditions and physical properties of liquids on the drag and added moment of inertia coef®cients were then evaluated, and empirical relationships which estimate values of these coef®cients, useful to predict the unsteady behavior and magnitude of agitation torque, were presented. Furthermore, equations were developed for estimating the average and maximum power consumptions as a function of the drag and added moment of inertia coef®cients. Prediction of respective power levels in AJITER by these equations was also discussed. # 2001 Society of Chemical Industry Keywords: unsteady torque; unbaf¯ed aerated agitated vessel; unsteadily rotating impeller; drag and added moment of inertia coef®cients; average and maximum power consumptions

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