涡轮增压器的流量测量PPT课件下载推荐.pptx

1、Concepts NREC,Flow Measurement,Nick Baines Concepts NREC,Other meters comprise a range of devices.Most of these also measure the flow rate indirectly via the drag force on an immersed body,workdone on a turbine,or a change in the electrical or acoustic properties of the medium.Only volumetric flow m

2、eters of the positive displacement type measure the flow rate directly,and do not find much application in turbomachinery.Other types of flow meter must be calibrated individually.,Concepts NREC 2,003,Flow measuring devices 1,Flow Measurement,Concepts NREC 2003,Flow measuring devices 2,Flow Measurem

3、ent,Concepts NREC 2003,Restriction flow meters,Venturimeter,Flow Measurement,Flow nozzles,Pressures must be measured at either D and D/2 taps or at flange taps.These must not be mixed and the prescribed measuring locations mustbe adhered to.At each point the pressure should be measured at several ci

4、rcumferential locations to give a reliable average.,Concepts NREC 2003,Orifice flow meter,Flow Measurement,Concepts NREC 2003,Orifice pressure loss,Flow Measurement,Concepts N,REC 2003,Orifice or nozzle flow meter,Flow Measurement,Concepts NREC 2003,Minimum pipe lengths,Flow Measurement,Concepts NRE

5、C 2003,Venturi meter,Flow Measurement,Calibration and checking,Build restriction flow meters to standards（e.g.ASME,HEI,BS）and use published calibrationsRequires very careful design and installation Accuracy is 12%at bestHave the meter checked at a standards laboratory（e.g.NBS）The standard is traceable in case guarantees are requiredExpensive and time-consumingDo the inlet and exit arrangements in the standards lab replicate those of the test rig?#Accuracy is 0.5%Concepts NREC 2003,Flow Measurement,