Vol-3 Issue-1 2017 IJARIIE-ISSN(O)-2395-4396 3653 www.ijariie.com 298 A Review of flow regime transition and pressure drop in two phase flow for vertical pipe Sethi Upasna Vijay 1 , Mansha Kumari 2 1 Assistant Professor, Mechanical Engineering Department, Vadodara Institute of Engineering College, Kotambi,Gujarat,India 2 Assistant Professor, Mechanical Engineering Department, Vadodara Institute of Engineering College, Kotambi,Gujarat,India ABSTRACT In this study, the flow patterns of air–water, two-phase flows have been investigated in a vertical mini pipe. Different flow patterns of air–water flow were observed simultaneously in the mini pipe at different values of air and water flow rates. Pressure drop prediction is investigated for vertical pipe in two phase flow. Pressure drop is causing more damage to vertical pipes as it has been many applications. Keyword: regimes, Surfactant: a substance which tends to reduce the surface tension of a liquid in which it is dissolved. 1. FLOW PATTERN TRANSITIONS IN VERTICAL FLOW The regimes encountered in vertical flows are illustrated in Figure 1. They include Bubble Flow, where the liquid is continuous, and there is a dispersion of bubbles within the liquid; Slug or Plug Flow where the bubbles have coalesced to make larger bubbles which approach the diameter of the tube; Churn Flow where the slug flow bubbles have broken down to give oscillating churn regime; Flow where the liquid flows on the wall of the tube as a film (with some liquid entrained in the core) and the gas flows in the center; and Wispy Annular Flow where, as the liquid flow rate is increased, the concentration of drops in the gas core increases, leading to the formation of large lumps or streaks (wisps) of liquid. Fig: Types of Vertical Flow Regimes 1.1 Pressure Drop Pressure losses occur in two-phase flow systems due to friction, acceleration and gravitational effects. If a fixed flow is required, then the pressure drop determines the power input of the pumping system. Here, examples are the design