Compressible Flow in Nozzles Thermal Engineering Lab ME-4111 Professor: Eduardo Cabrera Damian Luna Yetziel Sandoval – Alberto Gonzales – Fernando Fresse – Jaen Soto – 51080

Outline  Introduction and objective definition  Experimental Procedure  Experimental Results  Conclusion  Recommendation

Introduction  A Compress Flow is a changes in the fluid density, mostly gases can display this behavior but not liquids.  Nozzle is a device designed to control the direction or characteristics of a fluid flow (especially to increase velocity) as it exits (or enters) an enclosed chamber or pipe.

Objective  The objective of the present experiment is to understand the behavior of compressible flow through different types (3) of nozzles and have a good observation trough the three types.

Experimental Procedure In The experimental procedure we will be using the system for compress flow illustrated in the picture, by using the three assign nozzle for the experimental procedure.

Experimental Procedure  Shocking Effect Procedure (Nozzle C and A) The objective of this task is to demonstrate visually when the phenomenon of choking occurs. A. With the air inlet valve closed, fit Nozzle C (convergent) into the unit and connect all pressure tapping starting at position No.1. B. Select an inlet pressure Pi of around 700 kPa (gauge). Maintain the inlet pressure constant throughout the demonstration. C. Close the outlet pressure control valve (~backpressure valve) until the outlet pressure is equal to the inlet pressure (Po=Pi), therefore obtaining an air flow rate is zero. D. Gradually open the outlet pressure control valves allowing decrease the back pressures (Po gauge) while observing the air mass flow rate increase. E. Stop the outlet valve opening when the mass flow-rate stops increasing (maximum flow rate). F. At this point, record pressure gage Pi and Po and rotameter reading Mr in table 4.1.

Cont.  Constant Inlet Pressure Procedure (Nozzle C, A and B) The objective of this task is to demonstrate visually how pressure changes along a nozzle and identify visually it. A. With nozzle C fit in the unit, close the outlet pressure control valve and open the inlet pressure control valve and adjust its pressure Pi to 700 Kpa (gauge). Keep it constant. B. Open the outlet pressure control valve and adjust it pressure Po to KPa less than the inlet pressure. C. Complete Table 4.2. D. Decrease Po progressively in steps of 100 KPa until pressure is 0 KPa.

Cont.  The objective of this task is to demonstrate that the mass flow rate. A. With Nozzle C fit in the unit, close the outlet pressure control valve and open the inlet pressure control valve and adjust its pressure Pi to 700 kPa (gauge). B. Adjust the outlet pressure gage at 50 kPa (gauge). Keep this pressure constant. C. Complete the Table 4.3 recording the pressure gauges, thermometer and rotameter reading corresponding Pi. Reducing the inlet pressure in step of 100 kPa decrements until Pi= 50kPa (gauge). Replace nozzle C with A. Repeat steps indicated in manual to fill tables 4.4, 4.5 and 4.6. Replace nozzle C with B. Repeat steps Indicated in the manual to fill table 4.7.

Results

Calculation and Graphics

Cont.

 This graphs was develop by the table 4.11 of nozzle A.

Cont.

 This graphs was develop by the table 4.12 of nozzle

Cont.

Conclusion  For this particular experiment, the behavior of compressible flow was studied through nozzles. Three different kinds of nozzles were used Nozzle A (Long convergent-divergent type), Nozzle B (Short convergent-divergent type), and Nozzle C (Convergent type). Pressure data was collected at different conditions in order to obtain the maximum chocking condition of the flow and how the experimental behavior should be in accordance with expected ideal behavior. Chocking condition was found at for Nozzle C and for Nozzle A. It more than evident that the experimental condition was not to distant from theoretical condition

Recommendation  Switch the compressor with one that has more air capacity to avoid pressure lost in a fast rate.  Install a filter in the system to avoid water filtration in the system.  Fix the leaks that system has, to avoid pressure lost and have a better observation time.  Make sure rotameter is at cero point before you start the experiment.