ABSTRACT
This chapter looks firstly at the essential differences between laminar and turbulent flow and how calculation of the Reynolds number may be used to qualify the state of flow and therefore determine which flow measurement technologies may, or may not, be used.
The problems associated with disturbed flow profiles were then examined and how many of them may be overcome by the use of flow-conditioning devices. In this regard, we also looked at the shortcomings of the 19-tube bundle and at various other devices including flow-conditioning plates such as Laws, Spearman, MHI, Zanker, and Sprenkle as well as a number of proprietary conditioners including Vortab, CPA, and the Gallagher flow conditioner.
It was emphasised that any flow-conditioning device is a compromise between creating the best flow profile by eliminating swirl and at the same time producing a flow profile that approaches the ideal fully developed profile. Unfortunately, many of the flow-conditioning devices discussed incur significant pressure losses – typically up to 5 or more head loss coefficients – incurring both power and cost implications that can deter users from the use of such devices.
