Compressible Flow In Nozzles Orlando Matias Matias #59506 Thermal Engineering Lab Prof. Cabrera Polytechnic University of Puerto Rico Mechanical Engineering Department
Outline Objective Introduction Theory Experimental Procedure Calculation Conclusion Recomentations
Objective The objective of the present experiment is the behavior characterization of compressible flow through nozzle.
Introduction A nozzle is a pipe or duct, especially in a jet engine or rocket, that directs the effluent and accelerates or diffuses the flow to generate thrust. All gas turbines engines have a nozzle to produce thrust, to conduct the hot gases back to the free steam, and to set the mas flow rate through the engine. Nozzles are designed according to their application; however, they can usually be gathered as convergent, divergent ant convergent- divergent nozzles.
Theory Mach Number- Dimensionless parameter that measures the compressibility of the fluid flow. It is defined as the ratio between the velocity of sound of the fluid, which is employ to characterize the flow behavior.
Theory Flow through a Nozzle
Theory
Isentropic Flow in a Converging Nozzle
Isentropic Flow in a Converging- Diverging Nozzle
Discussion of Results Table 4.9Variation of air mass flow rate Inlet PressureActual Air mass flow rate obs Outlet Pressure Po (Kpa) Overall Pressure Ratio Po/Pi Nozzle ANozzle BNozzle C
Figure 4.9: Variation in Mass flow Rate
Table 4.11: Pressure Profile Data Nozzle A Table 4.11 Pressure Profile Data Nozzle A Obs. Pressure Ratio Px/Pi Outlet Pressure Po (Kpa) Overall Pressure Ratio Po/Pi Theoretical Value
Figure 4.11: Pressure Profile
Table 4.12: Pressure Profile Data Nozzle B Table 4.12 Pressure Profile Data Nozzle B Obs. Pressure Ratio Px/Pi Outlet Pressure Po (Kpa) Overall Pressure Ratio Po/Pi Theoretical Value
Figure 4.12: Pressure Profile
Table 4.13 Pressure Profile Data Nozzle c Obs. Pressure Ratio Px/Pi Outlet Pressure Po (Kpa) Overall Pressure Ratio Po/Pi Theoretical Value Table 4.13: Pressure Profile Data Nozzle C
Figure 4.13: Pressure Profile
Conclusion The objective is to understand the behavior characterization of compressible flow through nozzles. The three types of nozzles used in the experiment were classified by nozzle A, B and C. In table 4.1 and 4.4 “Data for choking effect” were realized with nozzle C and A respectively. Comparing the tables, with the same gage inlet pressure of 600 kN/m 2, the backpressure were 375 and 350 kN/m 2 respectively and the rotameter readings were and 3.76 g/s respectively. In conclusion, the nozzle C has more backpressure but less mass flow rate. The nozzle A has less backpressure but more mass flow rate. The factor of correction of the rotameter was In table 4.2, 4.5 and 4.7, “Constant Inlet pressure data for nozzle A, B and C, the effect of backpressure in nozzle C and B are very similar the values were around 650 to 0 kN/m 2. In the nozzle A was around 751 to 101 kN/m 2. In constant backpressure in nozzle A and B, all the values obtained were very similar. Comparing the graphs obtained, Variation in mass flow rate and pressure profile for the three nozzles, with the theoretical graphs were very similar as expected.
Recommendations The students need to be sure that the compressor is turned on and is full. Choose the right nozzle for the procedure.
Questions?