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SAE ARP492 Revision C, December 1, 1994
Aircraft Engine Fuel Pump Cavitation Endurance Test
Description / Abstract:
This SAE Aerospace Recommended practice (arp) defines procedures
for testing aircraft engine fuel pumps for the purpose of
determining their resistance to deterioration, during steady state
endurance test, while receivimg MIL-T-5624 Grade JP-4 fuel as a
homogenous mixture of gas and liquid expressed as a ratio of vapor
volume to liquid volume(v/l).
If any of the above conditions do not apply, refer to Section 2.
The Procedure recommended herein is based on experience gather by a number of laboratories conducting component qualification tests to MIL-E-5009, currently MIL-E-5007.it is intended to produce a uniform reprodudble steady state test condition for fuel pump cavitation testing as required by various military engine specifications.
This test is NOT intended to establish altitude, dimb rate, starting, or other transient performance of the article tested.
PURPOSE:
This procedure is intended to apply to al! pumps downstream of engine inlet.
The procedure will be defined in terms of recommended test setups and recommended testing methods.
Two methods of determining V/L are provided.
CAUTION: Operation at low line velocities may result in nonhomogeneous flows and cause erratic or incorrect readings.
Method I - V/L Meter: When using this method, the vapor-to-liquid ratio is sensed in a measuring section installed in inlet line upstream of the pump as shown in Figure 1. The vapor-to-liquid ratio is assumed to be the indicated volume flow rate vapor-to-liquid ratio and is read oul as V/L on a meter dial.
Method II - V/L Calculation: This method assumes that an equilibrium mass flow rate of dissolved air evolves from the flowing air saturated liquid fuel in accordance with Henry's Law for solution of gases in liquids. The volume flow rate vapor-to-liquid ratio is then calculated from the mass flows in accordance with Daiton's Law of Partial Pressures, the Perfect Gas Law and the liquid fuel thermal expansion behavior. The necessary calculations are described in Appendix A.
CAUTION: At low pump inlet pressures and/or high fuel temperatures, special care must be taken to obtain accurate readings of the test data that enter the V/L calculation. As can be seen from the V/L equation in Appendix A, a primary factor in the V/L calculation is the ratio of two pressure differentials measured during the test. If these pressure differential are small, as is the case when the tank pressure.P! (and, therefore, the pump inlet pressure P2) is close to the absolute true vapor pressure of the fuel, PtvP, even small errors in the measurements will cause large errors in the calculated value of V/L. A good practice in this connection would be the inclusion of note(s) on the test sheet calling attention to data points taken at low values of (PI-PTVP) together with the attendant estimated possible error in the calculated V/L resulting from measurement errors.
Recommended V/L Meters: Recommended V/L meters are listed in Appendix B.
Within this document the term "pump inlet" shall define the fuel inlet port of the complete system to be tested. If lines or other components are placed upstream of the inlet of the actual pumping component by specific test requirement, such as to provide an engine inlet, they shall be part of the complete system to be tested.
If any of the above conditions do not apply, refer to Section 2.
The Procedure recommended herein is based on experience gather by a number of laboratories conducting component qualification tests to MIL-E-5009, currently MIL-E-5007.it is intended to produce a uniform reprodudble steady state test condition for fuel pump cavitation testing as required by various military engine specifications.
This test is NOT intended to establish altitude, dimb rate, starting, or other transient performance of the article tested.
PURPOSE:
This procedure is intended to apply to al! pumps downstream of engine inlet.
The procedure will be defined in terms of recommended test setups and recommended testing methods.
Two methods of determining V/L are provided.
CAUTION: Operation at low line velocities may result in nonhomogeneous flows and cause erratic or incorrect readings.
Method I - V/L Meter: When using this method, the vapor-to-liquid ratio is sensed in a measuring section installed in inlet line upstream of the pump as shown in Figure 1. The vapor-to-liquid ratio is assumed to be the indicated volume flow rate vapor-to-liquid ratio and is read oul as V/L on a meter dial.
Method II - V/L Calculation: This method assumes that an equilibrium mass flow rate of dissolved air evolves from the flowing air saturated liquid fuel in accordance with Henry's Law for solution of gases in liquids. The volume flow rate vapor-to-liquid ratio is then calculated from the mass flows in accordance with Daiton's Law of Partial Pressures, the Perfect Gas Law and the liquid fuel thermal expansion behavior. The necessary calculations are described in Appendix A.
CAUTION: At low pump inlet pressures and/or high fuel temperatures, special care must be taken to obtain accurate readings of the test data that enter the V/L calculation. As can be seen from the V/L equation in Appendix A, a primary factor in the V/L calculation is the ratio of two pressure differentials measured during the test. If these pressure differential are small, as is the case when the tank pressure.P! (and, therefore, the pump inlet pressure P2) is close to the absolute true vapor pressure of the fuel, PtvP, even small errors in the measurements will cause large errors in the calculated value of V/L. A good practice in this connection would be the inclusion of note(s) on the test sheet calling attention to data points taken at low values of (PI-PTVP) together with the attendant estimated possible error in the calculated V/L resulting from measurement errors.
Recommended V/L Meters: Recommended V/L meters are listed in Appendix B.
Within this document the term "pump inlet" shall define the fuel inlet port of the complete system to be tested. If lines or other components are placed upstream of the inlet of the actual pumping component by specific test requirement, such as to provide an engine inlet, they shall be part of the complete system to be tested.
SAE ARP492 Revision C, December 1, 1994
Aircraft Engine Fuel Pump Cavitation Endurance Test