Embedded Files
Spaceflight Honeycomb Panel
Depressurization Project
Emma Fickett | Emily DeBoer | Hailey Griffith
Final assembled hardware
Our Goal
Our Goal
Our project’s motivation is to be able to both verify and eventually replace theoretical porous resistance coefficients (PRCs) with more accurate, experimental values. Since the PRCs are constant and proportional, we can solve for them by varying the mass flow rate and recording the pressure drop. Using the data collected, we are able to fit a curve and find the slope—the PRCs.
CAD render of inlet and outlet chambers with the variable mounting device.
Our Solution
Our Solution
Our project consists of a testing chamber that is able to attach multiple size samples from different honeycomb panels and sensors to measure the critical values that determine both the air flow characteristics and pressure drop across the sample.
The test chamber has a vacuum pump to facilitate steady state flow, two testing chambers each with sensor ports, a variable mounting device capable of accommodating multiple sample sizes, sensors, and data acquisition.
Supporting Analysis
Supporting Analysis
ATA’s CFD analysis provided a solution within ±10% error, therefore to be more accurate and replace these values, all sensors and equipment combined must be less than that error margin.
Test Results
Test Results
Final Result
Final Result
Experimental pressure drop vs mass flow rate of air using four different flow rates. Steady state values were used from each test and then a line was best fit to the data to compare with the theoretical curve.
To fully characterize the honeycomb sample, multiple flow rates must be tested and taken to a steady state regime.
Four flow rates (1, 2, 3, and 3.5 liters per minute) were chosen to showcase a wide range of pressure drops that our system could handle. Each test was conducted for five minutes each to allow the pressure drop to become stable.
Analyzing the data yielded experimental PRCs that were within an error margin of 12.7%, and showed that we could successfully measure and calculate porous resistance coefficients from a physical sample.
Additional Results
Additional Results
Using the theoretical relationship between pressure and flow rate, we were able to calculate the individual PRCs at separate flow rates, which were tabulated to the right.
These were each compared to the theoretical constant and the error was averaged to be 12.7% between all tests.
The error may be caused by undiscovered leaks in our system, sensor noise, sensor calibration, or even an inaccurate theoretical vent hole diameter that would exacerbate our error exponentially.
U_s is the bulk velocity and factors into the volumetric flow rate.
The four mass flow rate tests can be seen below. A steady state threshold was used to isolate areas where mass flow and pressure drop were constant, then plotted to our final graph (seen above), and used to calculate the porous resistance coefficients.
The four mass flow rate tests can be seen below. A steady state threshold was used to isolate areas where mass flow and pressure drop were constant, then plotted to our final graph (seen above), and used to calculate the porous resistance coefficients.
1 LPM Testing
2 LPM Testing
3 LPM Testing
3.5 LPM Testing
During each run through of testing, the data acquisition system stored time, differential pressure, absolute pressure, and volumetric flow data. The volumetric flow can be converted to mass flow rate by multiplying by the density of air. Each test's data is graphed vs time after the test is completed.
Post-test, the data was processed by using a rolling average to smooth out noise in the system and a steady state threshold separated each vector into usable data to be passed into the PRC equation. These steady state data points are also the clusters that are seen on the "Final Result" graph with different pressure drops at different flow rates.
In the future, repeatability testing will substantially help with error management and consistency of results.
The volumetric flow rate (LPM) is displayed on the MATLAB console alongside the pressure differential (psi) as real-time feedback for the user to accurately and precisely manipulate the flow rate to the desired points.
Page updated
Report abuse