Flow Mechanism in a 90° Miter-Tee : Part 1-Flow Pattern of Laminar Flow

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  • 90°対向型分岐管内の流動機構 : 第1報-層流における流動様相
  • 90°対向型分岐管内の流動機構-1-層流における流動様相
  • 90 タイコウガタ ブンキカンナイ ノ リュウドウ キコウ 1 ソウリュウ ニ

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Abstract

A miter-tee is frequently used in industry. But its flow mechanism has scarcely been clarified in detail. So, in the first place, the flow pattern in a miter-tee with the branching angle of 90° and the sharp-edged corners of the lateral entrance, which is a most fundamental shape, was studied for laminar flow. But the areal ratio m was chosen to be equal to 1.0, 1.5 and 2.0. The Reynolds number Re_<1h> was taken to be less than or equal to 200. The obtained results are summarized as follows: 1) The Navier-Stokes equations describing the steady, two-dimensional, laminar flow field of incompressible fluid in the miter-tees were solved numerically by means of a finite difference relaxation method when Re_<1h>, covered a range between 1 and 200. The influence of m, Re_<1h> and the ratio of lateral discharge to total discharge Q_3^*/Q_1^* upon the flow through the miter-tee was investigated. Generally, the effect of the flow dividing in the lateral conduit is larger than that in the main conduit. Also, its degree in the lateral conduit grows when the separation from upstream edge of the lateral entrance occurs. 2) The flow field in the real miter-tees was studied experimentally by means of a flow visualization technique when Re_<1h> covered a range between 5 and 200. The flow pattern is observed to be very complex when Re_<1h>≧70. But the flow adjacent to the center-line plane is always observed to be two-dimensional, and at Q_3^*/Q_1^*=0.0 a portion of the flow from the upstream section of the main conduit is observed to flow into the lateral conduit shut off independently of m and Re_<1h>. 3) The results obtained by the numerical analysis and the experiment coincide qualitatively well. When Re_<1h> is sufficiently small or Re_<1h> is large but Q_3^*/Q_1^* is small, both results coincide quantitatively well.

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