Internal Flow Systems (2nd) edition

Transient Analysis

Background

Transient events in piping systems have and unfortunately will continue to kill people, cause damage, loss of production and product, pollution and consequential and legal costs. The fact that systems fail or experienced operating problems from transient events requires that engineers, designers and operators carry out due diligence related to fluid transients. Design and operating teams should at least go through a checklist on all flow systems that could conceivably be subjected to transient events and take appropriate action.

My experience of investigating transient problems in industrial plant led me to conclude that handbooks on fluid transient did not deal with, or put into context, many of the events leading to problems with transient flows in industrial flow systems. Even with a good understanding of fluid transients it is not always possible to explain why or how excessive pressures were generated.

The history of transient analysis is dominated by pressure surges and water hammer in hydroelectric, water supply and sewage systems and this is reflected in the handbooks on transient analysis. The first edition of Internal Flow Systems had a Chapter on fluid transients. I did not include this Chapter in the second edition as I thought that a subject requiring computer based solutions was out of place in the book. From comments I received after publication of the second edition I realised that not including an introduction to fluid transients was a mistake because often engineers and designers needed information to make a judgement on whether or not to commission a fluid transient study.

Increasingly, flow systems are analysed using computer programs in which systems are modelled by assembling modules representing components such as pumps, valves, pipes and bends. The more capable of these programs, such as Flowmaster, simulate steady state and transient flows using virtually the same model. This speeds up the design and optimisation of flow systems and fits within integrated design environments. A design team is likely to have a better understanding of a particular flow system than a transient analysis Consultant, but a design team needs the appropriate level of knowledge of fluid transients to carry out valid fluid transient studies.

Flow system failures occur through a number of flow events that are not not classed as fluid transients. Due diligence studies should consider these events alongside transients. These events include:

Thermal Driven Events - Covering Heat transfer and condensation driven events
Fluid Structure Interactions - Covering flow-induced vibrations and fluid-structure interactions
Acoustic Resonance - Covering flow induced acoustic effects

Go to Transient Analysis

Home

Site is under development