1. Compressible Flow In Nozzles Orlando Matias Matias #59506 Thermal Engineering Lab Prof. Cabrera Polytechnic University of Puerto Rico Mechanical Engineering Department

2. Outline Objective Introduction Theory Experimental Procedure Calculation Conclusion Recomentations

3. Objective The objective of the present experiment is the behavior characterization of compressible flow through nozzle.

4. 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.

5. 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.

6. Theory Flow through a Nozzle

7. Theory

8. Isentropic Flow in a Converging Nozzle

9. Isentropic Flow in a Converging- Diverging Nozzle

10. 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 17510.9380.003200.00280.0019 26010.9290.003200.00320.0026 35510.7860199710.003570.00380.0030 44510.6430.003760.0038 53510.5010.003760.00390.0038 62510.3580599140.003760.00380.0036 71510.2150.003760.00380.0036 81010.1440798860.003760.00380.0034

11. Figure 4.9: Variation in Mass flow Rate

12. 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 0.751.52.2533.754.55.256 Theoretical Value 17510.9380.9750.8250.8500.8750.9000.9250.9500.950062 26510.9291.0000.8000.8290.8570.8860.9140.9430.942939 35510.7860.9710.629 0.7150.743 0.7720.771755 44510.6431.0000.601 0.629 0.6580.657632 53510.5010.9710.6010.3720.4010.4580.4860.5440.543509 62510.3581.0000.6010.3720.287 0.3150.3440.343795 71510.2151.0000.6010.3720.2580.2300.2010.1440.14408 81010.1441.0000.6010.3720.2870.2300.1730.1440.14408

13. Figure 4.11: Pressure Profile

14. 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 0.751.52.2533.75 Theoretical Value 17510.9380.97500.8750.900 0.925 26510.9290.94290.829 0.8570.886 35510.7860.88590.6580.6290.6860.772 44510.6430.91440.5720.4580.5440.601 53510.5010.85730.5440.3440.3150.429 62510.3580.88590.5440.3720.3150.287 71510.2150.88590.5440.3440.3150.258 81010.1440.88590.5720.3720.3150.287

15. Figure 4.12: Pressure Profile

16. Table 4.13 Pressure Profile Data Nozzle c Obs. Pressure Ratio Px/Pi Outlet Pressure Po (Kpa) Overall Pressure Ratio Po/Pi -6.25-5.25-4.25-3.25-1.25-0.05 Theoretical Value 17510.9380.9750.8250.8500.8750.9000.925 26510.9291.0000.8000.8290.8570.8860.914 35510.7860.9710.629 0.7150.743 44510.6431.0000.601 0.629 53510.5010.9710.6010.3720.4010.4580.486 62510.3581.0000.6010.3720.287 0.315 71510.2151.0000.6010.3720.2580.2300.201 81010.1441.0000.6010.3720.2870.2300.173 Table 4.13: Pressure Profile Data Nozzle C

17. Figure 4.13: Pressure Profile

18. 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 3.384 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 0.94. 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.

19. Recommendations The students need to be sure that the compressor is turned on and is full. Choose the right nozzle for the procedure.

20. Questions?