باستدراج تتابعي نكتب موضوع النوزل كونه البوابة العملية لمرور المائع لتغير بعض الخواص *وكما اسلفنا بالمواضيع ذات الشان والارتباط كالتوربينات وبهدف التنويه والاشارة الى التقاطع العلمي بين هذه المواضيع *نرفق لكم طيا ما وجدناه في صفحات النت حول هذا الموضوع وسنضع ما لدينا من ملفات كمرفقات لنسهل عملية البحث للاخوة الاعضاء *
ومن الله التوفيق*
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Introduction
Nozzles are used to determine a fluid's flowrate through a pipe. The ISA 1932 nozzle was developed in 1932 by the International Federation of the National Standardizing Associations (later succeeded by the International Organization for Standardization or ISO). The ISA 1932 nozzle is commonly used outside of the USA (ASME, 1971). The long radius nozzle is a variation of the ISA 1932 nozzle. The venturi nozzle is a hybrid having a convergent section similar to the ISA 1932 nozzle and a divergent section similar to a classical venturi tube flowmeter. The venturi nozzle shown above is called a "truncated" venturi nozzle because the divergent section does not extend smoothly to the pipe diameter (ISO, 1991). The divergent portion of a "non-truncated" venturi nozzle is longer and extends smoothly all the way to the pipe diameter. The discharge coefficients are the same for both types of venturi nozzles.
Differential pressure is the pressure difference P1 - P2 shown in the above diagrams. For exact geometry and specifications for nozzles, see ISO (1991) or ASME (1971). Nozzles are typically used in 5 to 50 cm diameter pipes. The ASME (American Society of Mechanical Engineers) and ISO have been working on guidelines for nozzles since the early 1900s. The organizations have the most confidence in nozzle accuracy when the Reynolds number is in the range of 104 to 107 as discussed below. The calculation above is for liquids. Gas flow calculations have an additional factor called expansibility.
Equations
The calculations on this page are for nozzles carrying a liquid as described in ISO (1991) and ASME (1971). The ISO reference has a more complete discussion of nozzles than the ASME reference, so the ISO equations are used in our calculations.


k = Equivalent Roughness of the pipe material [L]. Click for k values.
w is the static pressure loss occurring from a distance of approximately D upstream of the nozzle to a distance of approximately 6D downstream of the nozzle. It is not the same as differential pressure. Differential pressure is measured at the exact locations specified in ISO (1991) (shown in the above figures). Km is computed to allow you to design pipe systems with nozzles and incorporate their head loss. Head loss is computed as h=KmV2/2g where V is the pipe velocity