MH/T 6116-2018Test method for flammability of oil burners of magnesium alloy structure for aviation seats (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009.

This standard was proposed by the Aircraft Airworthiness Certification Department of the Civil Aviation Administration of China.

This standard is under the jurisdiction of the China Academy of Civil Aviation Science and Technology.

Drafting organization of this standard. The Second Research Institute of Civil Aviation Administration of China.

1 Scope

This standard specifies the test method for testing the flammability of magnesium alloy structural materials for aviation seats using high-strength, open flames.

This standard applies to the assessment of the flammability of magnesium alloy structural materials for aviation seats.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article Pieces. For undated references, the latest version (including all amendments) applies to this document.

CCAR-25-R4 Airworthiness Standard for Transport Aircraft

3 Terms and definitions

The following terms and definitions apply to this document.

Magnesium alloy

Based on magnesium, solid alloy composed of other elements (such as zinc) or rare earth elements (such as yttrium) is added, and the magnesium content in the alloy (The mass ratio) exceeds 10%.

Melting

The specimen is sufficiently relaxed to cause the main part to break freely and fall to the tray.

Note. Bending, twisting or unilateral sagging is not considered as melting.

Ignition

When the sample is burned by flame, it is the first time to observe the appearance of the sample which can be distinguished from the yellow-orange flame produced by the surrounding burner.

A very bright and intense blue-white flame.

Burning

The sample starts to ignite and lasts for more than 10 s.

Note. Does not include the interruption of combustion and reignition.

The percentage weight loss the difference between the weight of the sample before the test and the total weight of the sample and drips after the test, as a percentage of the weight of the sample before the test.

4 Equipment

5 Sample

6 Equipment debugging

7 Flame temperature calibration

7.1 Check the size of the combustion tube and clean the soot and other foreign objects on the combustion tube.

7.2 Install the thermocouple rake on a movable support and move it quickly to the calibration position in front of the combustion tube. Confirm that seven thermocouples arrive the distance between the exit end of the combustion cylinder is 102 mm±3 mm. Align the fourth thermocouple at the center of the exit end of the combustion tube. Confirm seven thermocouple tips the distance from the end to the horizontal centerline of the combustion tube is 25 mm ± 2 mm, see Figure 5.When all distances and positions have been confirmed, the thermocouple rake Move away.

7.3 Turn on the preheat, air and fuel switches, and ignite. Preheat the burner for 2 minutes, and then move the thermocouple rake to the calibration position. stable After 1 min, the temperature of each thermocouple is recorded every second within a time range of 30 s. After calibration, remove the thermocouple rake and turn off the flame. meter Calculate and record the average temperature of the thermocouples during the collection period. The average temperature of the seven thermocouples should be 927 °C ± 38 °C. If the temperature is not in this range it should be readjusted to make the flame temperature meet the requirements.

8 Test procedure

8.1 Check and clean the soot and residue on the combustion tube.

8.2 Weigh the weight of the sample before the test and record it as m1.

8.3 Install the sample according to Figure 2.The distance from the fire surface of the sample to the exit surface of the combustion tube is 102 mm ± 3 mm, and the center line of the sample is in the combustion tube 25 mm±2 mm above the horizontal centerline.

8.4 Move the sample holder to the preheating position. During the preheating process, the distance between the combustion tube and the sample should not be less than 46 cm, and the flame should not touch the sample.

Turn on the burner and stabilize for 2 minutes.

8.5 Move the sample holder to the test position and start timing.

8.6 Record the melting time, ignition time and test phenomena during sample burning, such as banging, explosion, smoke, etc. and each phenomenon Time of occurrence.

8.7 Test for 4 minutes, then slowly move the sample holder to the preheating position and turn off the flame.

8.8 Continue to observe the specimen after moving from the test position. If the sample is still burning, record the self-extinguishing time when the flame goes out.

8.9 Within 1 h after the end of the test, after the sample has cooled, loosen the hinged clamp and remove the sample. Collect the solidified melt in the tray and remove the oxide and talc are weighed together with the removed sample after the test, and recorded as m2.

8.10 Calculate and record the weight loss rate of the sample according to the following formula.

9 Test report

9.1 The sample material shall be fully described, including the manufacturer, material designation, alloy chemical composition and content, etc.

9.2 The melting time, ignition time and self-extinguishing time of each sample shall be reported.

9.3 The weight loss rate of the sample should be reported.

9.4 The test phenomena during the burning of the sample, such as banging, explosion, smoke, etc., and the time of each phenomenon should be reported.

9.5 The calibration record of the burner flame temperature should be attached.

Appendix A

(Informative appendix) Burner structure A.1 Burner A.1.1 General this appendix describes the details of the sonic burner, see Figure A.1.The sonic burner is a gun type, which is pressurized and atomized by fuel to combine with air.

Co-ignition produces a cone flame. Compressed air passes through a sonic throttle to produce combustible air. The combustible air passes through a series of diffuser blades.

The cylindrical ventilation pipe conducts. The diffused combustible air is mixed with the fuel sprayed from the nozzle in the conical combustion tube, and the fuel-air mixture passes through the fire the flower plug ignites and burns. The flame characteristics are adjusted by changing the air pressure.

A.1.4 Air pressure regulator the air pressure regulator is the key to maintaining the stable air flow of the burner. The air pressure regulator should include NPT 1 internal thread interface, including at least one A sub-interface for measuring outlet pressure, the pressure range should be greater than the normal working pressure range of the burner. The air pressure regulator should be able to maintain the test for the pressure required during the inspection, the schematic diagram of the air pressure regulator is shown in Figure A.8.

Figure A.8 Schematic diagram of air pressure regulator

A.1.5 Air pressure gauge the air pressure gauge should be calibrated by measurement, with an accuracy of at least ±2%. The schematic diagram of the air pressure gauge is shown in Figure A.9.Digital display air pressure gauge Calculate that the reading increment is not more than 6.89 kPa (1 psi). If other similar air pressure gauges are used, they should be filled with glycerin to reduce pointer chattering.

And need a readable dial.

Figure A.9 Schematic diagram of air pressure gauge

A.1.6 Muffler

The muffler is used to reduce the high frequency noise generated when the air diffuses in the throat of the sonic throttle. The outer diameter of the silencer is 76.2 mm (3 in), two the internal thread of the end interface is NPT 211, the total length is 305 mm (12 in), and there is no baffle and duct inside, see Figure A.10.Low flow resistance should be used Urethane foam reduces noise in the burner. The outer diameter of the foam is 76 mm (3 in) and the length is 305 mm (12 in). Should be at the outlet of the muffler the inner mesh is pasted with two wires that are arranged vertically and crossed to prevent the foam from being exposed to the muffler shell. Sonic throttle through hexagon bushing and right angle the elbow joint is connected to the muffler. The internal thread of the hexagonal bushing is NPT 1, and the external thread is NPT 211.The internal thread of one end of the right-angle elbow joint is NPT 11, the external thread on the other end is NPT 211.

Figure A.10 Schematic diagram of silencer

A.1.7 stator and turbulator A.1.7.1 The stators and turbulators are used to deflect and disperse airflow. The stator slides on the fuel pipe and is fixed with a positioning screw, see picture A.11.The turbulator is installed at the end of the ventilation pipe, and the identification plate is installed at the 6 o'clock direction, see Figure A.12.The front surface of the stator to the tip of the fuel nozzle the straight length is 63.5 mm (2.5 in), see Figure A.13.

Figure A.11 Schematic diagram of the installation position of the stator and fuel pipe

Figure A.12 Schematic diagram of the installation position of the turbulator

Figure A.13 Schematic diagram of the installation position of the stator and turbulator

A.1.7.2 The stator is an internal component with four blades, which causes the air to produce a swirling flow, see Figure A.14.The outer diameter of the stator is 101.6 mm (4 in), along the inner central axis of the vent pipe, align with the fuel pipe and install it tightly with the vent pipe.

Figure A.14 Schematic diagram of fixed film

A.1.7.3 Adjust the position of the stator. The distance from the front surface of the stator to the outlet end of the turbulator should be 68.3 mm±0.5 mm (2.6875 in± 0.020 in), see Figure A.15 and Figure A.16.

Figure A.15 Front view of the installation position of the stator and turbulator

Figure A.16 Side view of the installation position of the stator and turbulator

A.1.7.4 The turbulator is a vortex component with an outer diameter of 101.6 mm (4 in) and is installed at the port of the ventilation pipe. The central aperture is 69.85 mm (2.75 in), see Figure A.17.

Figure A.17 Schematic diagram of turbulator

A.1.8 Combustion tube A.1.11 Spark plug wire layout the wire length and arrangement of the spark plug should be prevented from being damaged by heat during flame calibration and testing. The wire layout should prevent contact the combustion tube and other hot surfaces should be covered with heat-resistant materials for thermal protection to prevent damage by the heat of the burner flame. The wire should be pressed

Figure A.23 Layout.

Figure A.23 Schematic diagram of spark plug wire layout

A.2 Fuel system

A.2.1 Oil supply system the fuel is delivered to the nozzle under pressure to produce continuous atomization. The fuel pressure is usually 689 kPa~827 kPa (100 psi~120 psi).

This range should be maintained during the test. If the pressure fluctuation is small, a fuel pump can also be used instead.

A.2.2 Fuel pressure gauge the pressure gauge should be measured and calibrated, with an accuracy of at least ±2%. The reading increment of the digital pressure gauge is not more than 6.89 kPa (1 psi), see figure A.24.If you use other similar pressure gauges, you need to fill it with glycerin to reduce pointer chatter, and you need a readable dial.

Figure A.24 Schematic diagram of fuel pressure gauge

A.2.3 Fuel temperature During the test, the fuel temperature should be maintained at 0 °C ~ 11 °C, through the heat exchange system, see A.3.

A.2.4 Fuel pipe

The design of the fuel pipe in the burner should make the fuel nozzle, air and the central axis of the ventilation pipe aligned. The fuel pipe is steel pipe, both ends the thread is NPT 1/8.The outer diameter of the catheter is 10.3 mm (0.405 in), the inner diameter is 5.5 mm (0.215 in), and the tube wall thickness is 2.4 mm (0.095 in). The total length of the catheter is 546 mm (21.5 in), the end length is 102 mm (4 in), and the outer diameter is 9.5 mm (0.375 in).

According to Figure A.25, use the pipe bending device to make the steel pipe into the size shown. Use strong thread sealing tape to wrap the threaded port to prevent oil leakage. Burn One end of the oil pipe is threaded to the nozzle joint, and the other end is fixed at the end of the tail with a keyless bushing and connected to the oil supply system pipeline.

Figure A.25 Schematic diagram of fuel pipe

A.2.5 Fuel nozzle

The configuration of the fuel nozzle of the burner is screw-in, 80° cone spray type. At fuel pressure 689 kPa~827 kPa(100 psi~120 psi) Within the range, the fuel flow rate of the nozzle should be 0.126 L/min ± 0.0063 L/min (2 gal/h ± 0.1 gal/h) to make the burner produce Suitable flame shape.

A.2.6 Nozzle connector the nozzle joint is made of brass, the internal thread of the inlet is NPT 1/8, and the outlet is connected to the fuel nozzle. The length of the nozzle joint is 34.9 mm (1.375 in), see Figure A.26.

Figure A.26 Schematic diagram of fuel nozzle

A.3 Heat Exchange System the heat exchange system is used to adjust the inlet air temperature and fuel temperature of the burner. The schematic diagram of the heat exchange system is shown in Figure A.27, which can also be used Alternative heating and cooling systems.

Figure A.27 Schematic diagram of heat exchange system

A.4 Measurement of burner inlet parameters A.4.1 Measuring position in order to obtain accurate burner inlet parameter measurement values, the pressure and temperature measurement positions of fuel and air should be as close to the burner as possible.

Entrance, see Figure A.28.In order to reduce the influence of the interruption of air flow, the inlet air temperature should be measured at the front of the sonic throttle.

Figure A.28 Schematic diagram of measurement location of inlet parameters

A.4.2 Inlet air pressure the inlet air pressure is measured by the air pressure gauge at the front of the sonic throttle. Effective measuring range of pressure gauge 0 kPa~414 kPa (0 psi~60 psi), the accuracy is at least ±2%.

A.4.3 Inlet air temperature the burner air temperature is measured by a K-type (nickel-chromium) thermocouple with a diameter of 3.2 mm (0.125 in), ceramic encapsulation, 310 stainless steel the sheath is grounded with 24 American standard wire gauge (AWG) wire or equivalent wire. The thermocouple should be inserted upstream of the sonic throttle. All entrances should be protected for the air piping, maintain the stability of the air temperature, and the inlet air temperature should be maintained at 5 °C ~ 15 °C.

A.4.5 Fuel pressure

The fuel should be properly pressurized to produce a suitable fuel flow. The fuel pressure range should be 689 kPa~827 kPa (100 psi~120 psi).

Use a suitable fuel pressure gauge to measure the pressure at the fuel inlet and the T-shape at the rear end of the burner.

A.4.6 Fuel temperature Burner fuel temperature measurement uses K-type (nickel-chromium) thermocouple, diameter of 3.2 mm (0.125 in), ceramic packing, 310 stainless steel Steel sheath, grounded with 24 American standard wire gauge (AWG) wire or equivalent wire. The thermocouple is installed through a T-joint and should be near the center of the fuel pipe.

In some test locations, the flame radiation may cause the fuel temperature to rise or the hose to burst. The fuel line should be protected to maintain the fuel temperature for stability, the inlet fuel temperature should be maintained at 0 °C ~ 11 °C. MH