Embedded Files
Spaceflight Honeycomb Panel
Depressurization Project
Components
Components
Chambers
Chambers
The inlet and outlet chambers serve as both structural components to house the sensor ports and hold the sample steady, as well as airflow control. The inlet chamber ensures fully developed and unidirectional flow by the point the airflow reaches the honeycomb sample. Similarly, the outlet chamber is airtight to ensure accurate pressure and mass flow readings, and additionally able to withstand the pressure of full vacuum if needed to achieve the desired pressure drop across the honeycomb panel sample.
Chamber Material Analysis
Chamber Material Analysis
For ensured safety, the outlet chamber must be capable of withstanding the full force of atmospheric pressure should the chamber reach complete vacuum.
Stress and failure analysis was conducted on the outlet chamber, using formulas from Roark's Textbook. A worst-case scenario was assumed of a uniform load on the largest rectangular face, with three edges simply supported and one edge free.
Largest surface - 8”x18”
¼” plate thickness
Atmospheric pressure - 14.7 psi
Yield strength - 35,000 psi
Weight - 6.75 lb/ft
Design stress - 11,900 psi
Factor of Safety - 2.93 (yield), 3.77 (fracture)
Conclusion: Extruded aluminum tubing is a safe and relatively lightweight material choice for chamber construction.
Variable Mounting Device
Variable Mounting Device
Mounting device CAD with both largest and smallest sample size
Ideal testing will include samples of multiple sizes to characterize the various commercially available honeycomb paneling.
The mounting device is necessary to direct the controlled airflow from the inlet chamber to the sample, and from the sample to the outlet chamber.
The main challenge of the mounting device is to maintain an airtight seal while providing adjustability in 3 dimensions.
Size Ranges
Size Ranges
3-7” width/length
0.4-2.1” thickness
Closed Cell Foam Backing
Closed Cell Foam Backing
Each wall is backed by closed cell foam. The closed cell foam is compressed by the screws to form a gasket and prevent air leakage.
Adjustable Width
Adjustable Width
The vertical walls of the mounting device are 3D printed to match the width of the sample.
The walls are actuated by 2 bolts that slide along T-slot brackets for additional range.
Adjustable Thickness
Adjustable Thickness
The mounting device provides continuously variable thickness adjustability, actuated by 2 sets of bolts and wing nuts.
Sensors
Sensors
All sensors are electronic, and readings will be saved to one output file
All sensors are electronic, and readings will be saved to one output file
Temperature sensor measures ambient air temperature at the inlet, used to calculate air density
Absolute pressure sensor can be attached to either inlet or outlet chamber ports, and is also used in air density calculations
Differential pressure sensor measures the pressure drop across the honeycomb sample
Mass flow sensor provides real time feedback for flow control
Porous resistance coefficients will be experimentally obtained by varying mass flow rate and measuring pressure drop during testing.
Pressure Sensors
Pressure Sensors
TruStability Differential Pressure Sensor
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TruStability Absolute Pressure Sensor
Mass Flow Meter
Mass Flow Meter
Posfia PMF6106V
Mass Air Flow Sensor
Temperature Sensor
Temperature Sensor
DS18B20 Programmable Resolution
1-Wire Digital Thermometer
Flow Control
Flow Control
Final flow control hardware.
Flow is produced by a pump at the end of the system.
A vacuum reservoir acts as a mass of air to mitigate oscillations in mass flow rate produced by the cycling motor of the pump.
The mass flow rate is controlled by a manual needle valve.
Flow Control Diagram
Flow Control Diagram
Needle Valve
Needle Valve
Easy-Set Threaded Precision Flow-Adjustment Valve
Vacuum Resevoir
Vacuum Resevoir
3 Gallon Resin Trap Vacuum Chamber
Stainless steel with separate inlet + outlet ports
Vacuum Pump
Vacuum Pump
Gast Standard Moa-P101-Aa Diaphragm Pump
Max output: 14 LPM
Data Acquisition
Data Acquisition
Image of final circuit board
Analog outputs from the electronic sensors are converted into a digital signals, processed, and finally stored in a single text file. These data outputs are then fed into a MATLAB script to calculate the porous resistance coefficient of the sample.
A 14 bit Arduino is used for data acquisition in this project.
Programs and scripts can be found here.
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