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Test #03-006, Advance Volume Sensors for Damage Control Project

DAMAGE CONTROL ENGINEERING TEST FACILITY

(DCETF)
NAVAL RESERVE CENTER, BALTIMORE
TEST DATA

TEST NUMBER: 03-006 DATE: May 14-15, 2003
TEST TITLE: Advance Volume Sensors for Damage Control project
TEST TEAM: Creig Beck
Susan Rose-Phersson NRL
Stephen Wales NRL
Daniel Gottuk Hughes Assoc.
Matthew Harrison Hughes Assoc.
RESULTS: A data collection was done by recording audio and video of damage bulkhead and rupture pipes. Result of these tests will be reported in Phase 3 from NRL, this should come out around the end of July. STATUS: Completed – Phase 2
EQUIPMENT NAME:
EQUIPMENT MANUFACTURER:
PHONE: 202-404-8149
AGENT: Steve Wales
FAX: 202-404-7813
  1. DESCRIPTION OF EQUIPMENT: Equipment that was used was the following: video, still cameras, audio recorder and signal analyzer.
  2. TEST OBJECTIVES: In this test the objectives are to record acoustic and monitor difference damages from flooding that maybe encounter onboard ship such as bulkhead and pipe ruptures. In this second testing phase a basic line test was conducted by recording audio and video of pipe rupture, bulkhead damage and spit seam damage in the DCETF. Phase 3 of this project is to supply video, sound recording, and report from NRL. Phase 3 is schedule for the end of July. NRL draft test plan is shown in enclosure 1. Sample pictures are also shown below.
  3. RECOMMENDATION:


Enclosure 1

NRL–DCETF Wet Trainer Test
Naval Reserve Center, Baltimore, MD
14-16 May 2003

Objective:

To determine if acoustic signals generated during ship compartment flooding can be used to identify the event, its severity and location with a sufficiently low false alarm rate and high probability of detection to be of practical use.

Background:

The human ear and brain identifies individual events by correlating the time-frequency content of a signal with a stored database (memory) developed over time. The probability of a human falsely identifying a specific audio event decreases over time as the brain’s database and comparative algorithms mature.

A machine-based audio event detector will be successful if the time-frequency signature of flooding events such as pipe rupture and subsequent water flow can be uniquely distinguished from other broadband shipboard sounds.

To determine if a broadband acoustic signal resulting from a flooding event can be used to uniquely identify the event a database of sound from a variety of flooding scenarios must be acquired to permit frequency and time-frequency signature characterization. These characteristics must be compared to common shipboard acoustic background sounds to determine if they can be distinguished in near-real time.

Approach:

A series of measurements will be recorded as representative of as many different scenarios as is practical. It is expected that trainer personnel will be most familiar with the sounds produced and the capabilities of the trainer and they will be relied on to provide guidance about possible tests or variation to the tests which might be of interest.

The presence of rain is a major detriment to useful measurements since it constitutes a noise source virtually identical in nature to the noise sources being measured. If the interference is too loud, tests will either be moved inside or suspended. It is intended that all tests would normally be conducted in the outside engineering test facility.

The tests are broken into six groupings with various objectives. They are listed roughly in order of priority. Changes may be made to the schedule based upon time constraints, weather, trainer personnel recommendations, or observations on the sounds already recorded.

The first five test groups call for the drain to be closed and the test to be run until the water level reaches a certain point. For the first four test groups that point is reached when the water-on-water impact noise is no longer changing with increased water depth. This could be as little as an inch for sprays, but may be significantly more for streams, several inches to a foot. Test group 5 is intended to test room effects and the room will be filled as much as possible within safety and time constraints. Test group 6 is conducted outside.

Test group 1:

  1. Flow rate (x3)
  2. Hole size (x3)
  3. Height of release (x3)
  4. Water depth on floor, none to a few inches (time)

The objective of this group of 27 tests is to characterize the gamut of dripping to spraying sounds. The drain will be closed for the test. When the room has filled to 3-6 inches of water, the test will be terminated and the drain opened. The next test will begin after the room is drained. For the higher flow rates, these tests could go fairly quickly. The flow rate will be calculated from the water depth, floor area, and the time of the run.

Test Group 2:

  1. Hole shape, slit to circular (x3)
  2. Flow rate (x3)

The objective of this group of nine tests is to characterize any differences due to hole shape. That is, does a slit produce a different sound than a more circular hole? The drain will be closed for the test. When the room has filled to 3-6 inches of water, the test will be terminated and the drain opened. The flow rate will be calculated from the water depth, floor area, and the time of the run.

Test Group 3:

  1. Hatch flooding (3)
  2. Open Valve (2)
  3. Leaking Patch (3)

The objective of this group of eight tests is to characterize special circumstances. The hatch flooding will be run at a low, medium and high flooding rate. The open valve will be run at a slow drip and full on. The leaking patch test will be run at three different pressures. The drain will be closed for the test. When the room has filled to 3-6 inches of water, the test will be terminated and the drain opened. The flow rate will be calculated from the water depth, floor area, and the time of the run.

Test Group 4:

  1. Compartment size (x3)
  2. Scenarios (x2)

The objective of this test is to determine the effect of room acoustics on the sounds. In three different compartments, two tests that are as similar as possible between the compartments will be run. The drain will be closed for the test. When the room has filled to 3-6 inches of water, the test will be terminated and the drain opened. The flow rate will be calculated from the water depth, floor area, and the time of the run.

Test Group 5:

  1. Flooding scenario (2)

The objective of this test is to determine how the room acoustics change as the room is flooded. Two tests will be run, one from an overhead pipe and the other from a source near the floor, which is quickly submerged. The drain will be closed for the test. When the room has been filled as high as possible/permitted, the test will be terminated and the drain opened. If a door or hatch can be safely opened, this will be done instead of using the drain. The flow rate will be calculated from the water depth, floor area, and the time of the run.

Test Group 6:

  1. Hole size/shape (x3)
  2. Pressure (x2)

The objective of this group of six tests is to measure the sounds of water sprays at the point of release. The measurements will be conducted outside with the water falling away from the point of spray. The microphones will be placed about 1 foot from the hole.

Test Equipment and Support Requirements:

The tests will be recorded with both audio and video equipment. The audio equipment will consist of two microphones, usually placed near each other, conditioning amplifiers, a DAT recorder, a computer and an oscilloscope. The cables from the microphones permit the recording equipment to be as much as 100 ft away. A table near standard A/C power is desired to set up the recording equipment and computer. The cables will need to enter the compartment at a height above the final water level for the experiment.

The video equipment will consist of a camera, recorder and monitor. Their requirements are similar to those for the audio equipment.

Test Matrixes:

The following test matrixes are provided to indicate a proposed sequence of tests. The stations will be assigned during the experiment. In addition, some of the comments will indicate, in some of the later test groups, that a previous test fulfills the requirements for that test. These tests are not repeated.

Test Group 1:

Test Station Hole Size Flow Rate Height Comments
1   Large Low Low  
2   Large Medium Low  
3   Large Full Low  
4   Large Low High  
5   Large Medium High  
6   Large Full High  
7   Intermediate Low Low  
8   Intermediate Medium Low  
9   Intermediate Full Low  
10   Intermediate Low High  
11   Intermediate Medium High  
12   Intermediate Full High  
13   Small Low Low  
14   Small Medium Low  
15   Small Full Low  
16   Small Low High  
17   Small Medium High  
18   Small Full High  
19   Large Low Intermediate  
20   Large Medium Intermediate  
21   Large Full Intermediate  
22   Intermediate Low Intermediate  
23   Intermediate Medium Intermediate  
24   Intermediate Full Intermediate  
25   Small Low Intermediate  
26   Small Medium Intermediate  
27   Small Full Intermediate  

Test Group 2:

Test Station Hole Shape Flow Rate Comments
1   Slit High  
2   Slit Intermediate  
3   Slit Low  
4   Circular High  
5   Circular Intermediate  
6   Circular Low  
7   Irregular High  
8   Irregular Intermediate  
9   Irregular Low  

Test Group 3:

Test Station Event Type Flow Rate Comments
1 F1 Hatch Flooding High  
2 F1 Hatch Flooding Intermediate  
3 F1 Hatch Flooding Low  
4 F1 Open Valve High  
5 F1 Open Valve Low  
6 F1 Leaky Patch High  
7 F1 Leaky Patch Intermediate  
8 F1 Leaky Patch Low  

Test Group 4:

Test Station Room Flow Rate Comments
1   Small High  
2   Small Low  
3   Medium High  
4   Medium Low  
5   Large High  
6   Large Low  

Test Group 5:

Test Station Height Comments
1   High  
2   Low  

Test Group 6:

Test Station Hole Shape Pressure Comments
1     High  
2     Low  
3     High  
4     Low  
5     High  
6     Low  

Sample pictures of the Test

Image of compartment flooding through hole in bulkhead Image of compartment flooding through hole in bulkhead