1. Asst. Prof. Dr. Hayder Mohammad Jaffal
Ministry of Higher Education &scientific Research
Mustansiriyah University
College of Engineering
Mechanical Engineering Department
Two- phase flow pressure drop caused by sudden expansion and contraction
(Section 6)
Asst. Prof. Dr. Hayder Mohammad Jaffal

2. Two- phase flow pressure drop caused by sudden expansion and contraction
Flow of two phase mixtures through sudden expansion and contractions are typically seen between the connection pipes as well as in the case for many applications such as chemical reactors and petrochemical plants. Frictional pressure drop can be noticed in sudden expansion and contraction of the tubes. This pressure drop can be added to the total pressure drop of the flow through the tubes.

3. 1- Pressure drop through sudden expansion
Figure (1) Definition of pressure drop subject to the influence of sudden expansion

4. For the two-phase pressure change across sadden expansion is :
Flow cross-sectional area contraction ratio can be calculated as:
For homogenous flow, the two-phase pressure change across sadden expansion is :

5. where

6. 2- Pressure drop through sudden contraction
Figure (2) Definition of pressure drop subject to the influence of sudden contraction

7. Where
For two-phase flow, the frictional pressure drop due to sudden contraction can be estimated using a homogeneous flow model as: