heat release rate updates 2014 june materials meeting switzerland

Federal AviationAdministration

HEAT RELEASE RATE Updates

2014 June Materials MeetingSwitzerland

Materials Working Group

Michael Burns, FAA Tech Center

June, 2014


Heat Release Rate Test ApparatusJune 2014

AGENDA

OSU

• Orifice Meter Discussion

(Static Pressure Taps)

CHAPTER HR UPDATE (HR2)

• Combined Supplement with Test method



• Protruding pressure taps (beyond the pipe inner wall) vs. surface pressure taps (flush with inner wall) may have a influence on pressure readings

• Could have an influence on total airflow

OSU:



Supplemental material moved to Test Method as follows: Added BTU/ft2*sec units

Environmental Chamber – Added Radiation Door Assembly Figure

Radiation Source

• Power Supply Capacity – 12 kVA is sufficient

• Diamond-Shaped Mask Mounting – ½ inch diameter machine screw

(approximately 4 inches in length)

• Mask Position – Approximately 3 inches from the reflector plate

• Mask shaft-head or nut only on side facing specimen

(no threads extending towards specimen)

HR2: HEAT RELEASE TEST METHOD



Thermopile Wiring

• Color coding differences - Chromel yellow/green; Alumel red/white

Upper Pilot Burner

• Caution Statement – Do not disturb burner position once set

• Flame Profile – To increase orange tip, reduce air from the mixture

Drill hole sizes added for:

• Upper Pilot Burner (#59 Drill)

• Air Distribution Plate (# 4 Drill)

• Second Stage Plate (# 28 Drill)

Drip Pan - Foil can be used to line the drip pan to facilitate cleaning after use




Heat Flux Gauge (HFG)

• Cooling Water Tubing – Rigid due to the high temperatures

• Cleaning – Gently wipe with soft, water-dampened sponge

• Caution Statement – Damage done to the coating during the cleaning process will affect the measurement accuracy of the sensor

Specimen Preparation

• Added recommended specimen foil wrapping technique

• Foil trimming – no scoring or incisions permitted

• Spring Plate Pressure – Recommended applying equal pressure to specimens of equal thickness by inserting the specimen retaining rod in the same holes for each specimen tested




Heat Flux Calibration Procedure (Corner)

• Caution Statement – Do not disturb burner position when rotating calibration fixture 90 degrees

• Added options for improving 4-corner uniformity:

Adjust power settings

Reposition globars - Hottest to coolest (bottom to top)

Move mask – Closer to or further from HFG

Move globars – Adjustment left or right

Reflector plate – Adjust slope (top and bottom)

Added Rounding, Accuracy and Units section




Calculation of Calibration Factor Kh – Added example assuming 60 mV baseline; 7 mV rise for each change in flow


Kh = 0.5879∗ሺF1 − F0ሻሺV1 − V0ሻ kW/mV

If:

Baseline Flow

(SLPM)

High Flow

(SLPM) Baseline

(mV)

High Flow (mV) Δ Flow Δ mV Kh

1 2 60 67 1 7 0.0840 1 3 60 74 2 14 0.0840 1 4 60 81 3 21 0.0840

Then: Kh = (Kh (1 → 2) + Kh (1 → 3) + Kh (1 → 4)) / 3 kW/mV Average Kh = 0.0840 kW/mV Cv = 0.0% (< 5% therefore calibration is valid)



Test Preparation

• Thermopile – Baseline mV observed daily as an indicator of developing problems

Variations in heat flux (heat flux gauge malfunction)

Defects in thermopile

Air leakage – Environmental chamber/lower plenum, exhaust stack or holding chamber door seal

Test Performance

• The use of an externally positioned mirror may assist in viewing upper pilot flames during testing




Heat Release Rate – Added example for calculating HRR (Peak HRR)


Heat Release Rate = ሺTestmV − BaselinemVሻ ∗ ቀ Kh0.02323 m2ቁ kW/m2

ሺTestmV − BaselinemVሻ ∗ ቀ Kh0.02323 m2ቁ kW/m²

If: BaselinemV = 60 [Average thermopile millivolt reading at baseline (mV)] TestmV = 81 [Thermopile millivolt reading at any point during test (mV)] Kh = 0.0840 [Calibration factor (kW/mV)] Then: Heat Release Rate = ሺ81 − 60ሻ ∗ ቀ0.08400.02323ቁ kW/m² = ሺ21ሻ ∗ ሺ3.62ሻ kW/m² = 75.93 kW/m²



Total Heat Release – Added example for calculating Total HR (2-Min. THR)


σ ൫Test mV − Baseline mV൯ ∗ ൬ Kh0.02323 m2൰n−1t=0 x kW · min/m² If: n = 120 [Total number of data collection points in 2 minutes] x = 60 [Total number of data collection points in 1 minute] BaselinemV = 60 [Average thermopile millivolt reading at baseline (mV)] TestmV = 81 [Thermopile millivolt reading at any point during test (mV)] Kh = 0.0840 [Calibration factor (kW/mV)] Scan # Heat Release Rate T = 0 75.93 T = 1 75.93 . 75.93 . 75.93 . 75.93 T = 119 75.93 TOTAL 9111.0 Then: Total Heat Release (After 2 minutes) = (9111.0 / 60) kW · min/m² = 151.9 kW · min/m²



Test Report

• Laboratory

• Fully identify the material tested

• Graphically report the heat release rate (kW/m2) as a function of time (in seconds) for each test

• Maximum heat release rate and time (in seconds) it occurs during each test

• Total heat released during the first 2 minutes of each test

• Radiant heat flux to the specimen




Test Report (Continued)

• Calibration factor Kh (kW/mV )

• Average mV baseline for each specimen tested

• Melting, sagging, delaminating, or other behavior that affected the exposed surface area or mode of burning that occurred and the time(s) at which such behavior occurred

• Total number of materials tested

• Total number of materials passed




Requirements

• Quantity of Samples – Minimum of three samples must be tested and 80% or greater must pass


Example

Total Samples Tested

Must Pass %

3 3 100%

4 4 100%

5 4 80%

6 5 83%

7 6 86%

8 7 88%

9 8 89%

10 8 80%

11 9 82%

12 10 83%



QUESTIONS?

What is full of holes, but can still hold a lot of water?Answer: Sponge

heat release rate updates 2014 june materials meeting switzerland

Documents

equal pressure

pressure readingscould

protruding pressure

burner position

surface pressure taps

recommended specimen

rightreflector plate

specimen testedhr2