105 90 75 .. 60 o, 45 30 15 o o 15 Figure 5a 105 90 75 ·O 60 o, .. 45 30 15 o o 15 Figure 56 105 90 75 60 45 30 15 o o 15 Figure 5c Test 2, ic is clear rhac a similar performance profile arises far ehe rhree syscems, once again ehe eleccronic syscem producing ehe more favourable resulcs. Whilrs ehe chree syscems have been compared 30 45 60 75 Percentage Output to Valve 30 45 60 75 Percentage Power Output to Valve 30 45 60 75 Percentage Power Outputto Valve DO�AL GAZ DERGiSİ SAYI. 28 139 90 in cerms of cheir abiliry co achieve an accurace AGR, it should be nored ebat each syscem differs signifıcancly. In pracrice it is nored ebat each sysrem comprises rwo incerconnecred operarions; namely measuremenc/dececrion and concrol/correccion. 105 The underlying fundamencal difference becween rhe sysrems is largely due co ehe parcicular valve characcerisrics; such characrerisrics being non linear in nacure The characrerisrics ebat are peculiar co each valve syscem are evidenr from ehe resules given in Figure 3a-3c and 4a-4c, by examinarion of ehe air and gas flows. This observarion leads narnrally ro an invescigarion inco ehe characreriscrs of ehe various valve rypes in an arcempr co idencify ehe salienc fearures affecring rheir behaviour. 4. VALVE CHARACTERISTICS Recognising rhar perhaps one of ehe main sources or operarionalerror in eheAGRsysrems lies wirhin ehe non-linear char90 105 accerisrics of ehe valves, ehe nexc phase of invesrigarive srndies has been co idencify rypical valve characcerisrics from a syscems modelling viewpoinr. In order co underrake such an invesrigacion requries access co operarional dara ofehe various valve rypes in real-rime. Figures 5a, 56 and 5c illusrrare ehe resulcing flows during ehe opening and closing ofehe valve posirion and correspond co a burrerfly valve, a square 90 105 porc valve, and a disc on seac valve respecrively. le is clear rhar whilsc each ofrhese valves suffer
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