CALCULATION OF AREA OF THROAT IN TURBINE NOZZLES. Stage Numbor. FORM B. Horse power of turbine 2000 184 STEAM-TURBINES. Water rate, 14.2 pounds per B.H.P hour. Total Water per second 7.9 pounds=W. 3 4 6 Initial absolute pressure at entrance to nozzles, from curve, PB,, PB, etc 165. 48 24.5 12.5 6.0 2.5 Degrees F. superheat at nozzle bowls. 100. 61. 39. 16. Temperature of saturated steam at bowl pressure, degrees F. 366. 278. 239. 203. 169. 134. Initial temperature at entrance to bowl, degrees F. 466. 339. 278. 219. 169. 134. Orifice pressure 577 PB,, 577PB, etc., pounds absolute 95. 27.7 14.2 7.2 3.46 1.44 Heat contents in bowl, IIB., IIB, etc., B.T.U. 1252. 1203. 1177. 1151. 1125. 1099. Heat contents in orifice, assuming ad, exp. (from chart), Ho.. Ho,, etc., B.T.U. 1208. 1160. 1150. 1120. 1095. 1070. Heat given up in orifice, HB,-lo, IB-Ho,, etc., BT.U. 44. 43. 27. 31. 30. 29. Efficiency of orifice, k₁, ky, etc. 0.96 0.95 0,92 0.92 0.90 0.90 Velocity of flow in orifice 224V(HB-HO), etc., Vo ft/sec Superheat in orifice, from chart, degrees F. 1460. 1430. 1120. 1195. 1165. 1145. 43. 5.0 2-0 Quality in orifice, from chart, per cent.. 97.5 96.0 95.0
- Specific volume at orifice pressure, and quality or superheat,
vo cu. ft.... 5.0 14.6 27.4 52.6 99.8 228. voXX144, Area of throat of nozzle = A sq. ins. . 3.9 11.6 27.9 50.2 97.6 227 Vo NOTE. For an expanding nozzle the value of A to be used in computing diameter of turbine is found by multiply- ing the above value by the expansion ratio of the nozzle.
- In cases of superheated steam in the orifices the values of ware to be taken from the curves following page 188.
