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Cooling Acoustics
Spring 2017 MAE 156B Sponsored Project
University of California, San Diego
Figure 1. CAD Final Test Setup
Figure 1. CAD Final Test Setup
Background:
Background:
Modern day airplanes encounter ice accretion on the leading edges when flying at holding conditions of 15000 ft for more than 1.5 minutes. This phenomenon occurs due to super cooled water droplets being present at this height. As the plane flies at this holding elevation, the droplets impact the plane and instantly solidify on the surface. This ice accretion causes decreased efficiency due to drag and imposes danger to the fan blades when ice chunks break off and flow into the engine.
To deal with this problem, many companies use pneumatic anti-icing where hot air is bled from the engine through a series of ducts to the nose-lip. This hot air is then circulated around the circumference of the nose-lip using a nozzle and heats up the aluminum lip through conduction and convection. The hot air can reach up to 772F at extreme takeoff and landing conditions.
In addition to stricter laws about noise pollution, airplane companies are going in the direction of higher bypass ratios with shorter nacelles for more efficiency. In order to reduce noise of the engine, the inlet is composed of perforated aluminum, allowing noise to enter the acoustic honeycomb structure. The structure is sized in a way that dampens noise using destructive interference of sound waves. With shorter nacelles, the inlet length is reduced. This also reduces the amount of acoustically treated area possible. One method to alleviate this problem is introducing acoustic honeycomb structure into the nose-lip. Originally just a hollow D-Duct, the structure now has an added thermal barrier to conduction.
Objective:
Objective:
1. Investigate temperature needed within D-Duct to anti-ice noselip surface with respect to honeycomb acoustic panel design.
2. Explore feasible and repeatable analytical and simulation methods.
3. Build prototype (8 in by 8 in) of optimal design to test and validate simulation results.
4. Finalize results to present and make recommendations.
Final Design:
Final Design:
Figure 2. Annotated Test Setup
Figure 2. Annotated Test Setup
Figure 3. Actual Test Setup
The final design placed an emphasis on being able to provide a wide variety of test experiments that can be simulated and compared with experimental data. The main goal of the design is to find the effective temperature gradient needed for de-icing. This resulted in the need to control both the high and low temperatures of each side of the honeycomb core panel, in addition to providing sources of convection. The heated side was encased in Calcium Silicate insulation to isolate the test panel from ambient air and create a quasi-adiabatic environment.
The design of the test setup revolved around utilizing a wind tunnel to funnel a steady flow of air from the fan onto the panel. The air can be cooled by placing a cooler of dry ice in front of the fan. The heater blanket was insulated on the bottom to force most of the heat transfer to occur upwards to the honeycomb panel.
The design of the test setup revolved around utilizing a wind tunnel to funnel a steady flow of air from the fan onto the panel. The air can be cooled by placing a cooler of dry ice in front of the fan. The heater blanket was insulated on the bottom to force most of the heat transfer to occur upwards to the honeycomb panel.
Summary of Performance Results:
Summary of Performance Results:
The results of our testing and simulations showed that THIS SHOULD BE USED HERE.
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