Though the differential pressure sensors were hard to analyze, there is a lot of potential in these sensors taking the sensitivity into account. With a higher pressure range, the sensors would have
been able to measure much more at the leading edge of the foil. These sensors would work better for lower Reynolds number. Another option is to place the holes on the surface and on a point in the freestream velocity, so that the actual Cp can be measured. To continue using this foil, one might need to look into making the holes more flush with the surface and making them less rough around the edges.
As the 3D effects were very significant, a much larger aspect ratio for a foil is recommended. A lifting line code should be made to estimate the effect of the 3D shape, so that stalling region can be predicted beforehand. It is helpful to measure up to higher angles of attack.
Differences in boundary layer are hard to observe on a small foil like this, for future boundary layer analyses, I recommend a more reliable setup in a cavitation tunnel, where high Reynolds flows can be created in a stable environment. One could observe boundary layer development on a flattened surface, where the development is more gradual and a longer distance than the chord length of a foil. This would be helpful for a superhydrophobic surface. A test setup where boundary layer separation can be observed easily is highly recommended.
The results from this research project suggest that coating a foil with a hydrophobic anti-fouling paint could shift the occurrence of stalling towards higher angles of attack. The potential rele-vance for marine vehicles should be evaluated further.
9 References
[1] Hermann Schlichting and Klaus Gersten. Boundary-Layer Theory. Springer Berlin Heidel-berg, Berlin, HeidelHeidel-berg, 9th ed. 2017 edition, 2017.
[2] Ira H Abbott. Theory of wing sections : including a summary of airfoil data, 2012.
[3] Frank M White. Viscous fluid flow, 2006.
[4] Odd M Faltinsen. Sea loads on ships and offshore structures, 1990.
[5] M. Drela. XFOIL. http://web.mit.edu/drela/Public/web/xfoil/, 2013. Accessed: 26-01-2019.
[6] Brian R. Elbing, Simo M¨akiharju, Andrew Wiggins, Marc Perlin, David R. Dowling, and Steven L. Ceccio. On the scaling of air layer drag reduction. Journal of Fluid Mechanics, 717(2012):484–513, 2013.
[7] M. J. Costa, J. F. Fuentes-Perez, I. Boavida, J. A. Tuhtan, and A. N. Pinheiro. Fish under pressure: Examining behavioural responses of iberian barbel under simulated hydropeaking with instream structures.(research article)(report). PLoS ONE, 14(1), 2019.
[8] C. Sarraf, H. Djeridi, S. Prothin, and J.Y. Billard. Thickness effect of naca foils on hydrody-namic global parameters, boundary layer states and stall establishment. Journal of Fluids and Structures, 26(4):559–578, 2010.
[9] F.E. Fish and G.V. Lauder. Passive and active flow control by swimming fishes and mam-mals. 38(38):193–224.
[10] ERIK J. ANDERSON, WADE R. McGILLIS, and MARK A. GROSENBAUGH. The boundary layer of swimming fish. Journal of Experimental Biology, 204(1), 2001.
[11] Juan F Fuentes-Perez, Kaia Kalev, Jeffrey A Tuhtan, and Maarja Kruusmaa. Underwa-ter vehicle speedometry using differential pressure sensors: Preliminary results. In 2016 IEEE/OES Autonomous Underwater Vehicles (AUV), pages 156–160. IEEE, 2016.
[12] James W Gose, Kevin Golovin, Mathew Boban, Joseph M Mabry, Anish Tuteja, Marc Perlin, and Steven L Ceccio. Characterization of superhydrophobic surfaces for drag reduction in turbulent flow. 845:560–580, 2018.
[13] P. W. ; Collicott Steven H. ; Valentine Daniel T. Houghton, E. L. ; Carpenter.Aerodynamics for Engineering Students. Elsevier Science, 6 edition, 2012.
[14] Zifeng Yang, Fred Haan, Hui Hu, and Hongwei Ma. An experimental investigation on the flow separation on a low-reynolds-number airfoil. In45th AIAA aerospace sciences meeting and exhibit, page 275, 2007.
[15] National advisory committee for aeronautics. https://web.archive.org/web/
20090427002114/http://www.fges.demon.co.uk/cfd/naca.html#07. Accessed: 11-03-2019.
[16] Jaedoo Lee V, Jungjoong Kim, Booki Kim V, Jinho Jang V, Paul Mcstay V, George Raptakis V, and Peter Fitzpatrick V. Full Scale Applications of Air Lubrication for Reduction of Ship Frictional Resistance Feasibility of Drag Reduction. 1(V):1–12, 2016.
[17] Noah Silberschmidt, Dominic Tasker, Takis Pappas, and Johannes Johannesson. Silver-stream R System – Air Lubrication Performance Verification and Design Development.
Shipping in Changing Climates Conference 2016, pages 1–12, 2016.
[18] Julio M. Barros Michael P. Schultz Anish Tuteja Marc Perlin Steven L. Ceccio James W. Gose, Kevin B. Golovin. Laser Doppler Velocimetry Measurements of A Turbulent Boundary Layer Flow over Sprayed Superhydrophobic Surfaces. 10th International Sym-posium on Turbulence and Shear Flow Phenomena (TSFP10), Chicago, USA, July, 2017, (V):1–12, 2017.
[19] Sintef ocean. https://www.sintef.no/en/all-laboratories/towing-tanks/. Accessed:
14-06-2019.
[20] Anton paar gmbh. https://wiki.anton-paar.com/en/water/. Accessed: 14-06-2019.
[21] Tommy Ness Torstensen, JOTUN A/S. Personal commmunication. 2019.
A MPXV7002 Differential Pressure Sensor
Freescale Semiconductor
Document Number: MPXV7002Data Sheet: Technical Data
Rev 3, 01/2015MPXV7002 Integrated Silicon Pressure Sensor On-Chip Signal Conditioned, Temperature
Compensated and Calibrated
The MPXV7002 series piezoresistive transducers are state-of-the-art monolithic silicon pressure sensors designed for a wide range of applications, but particularly those employing a microcontroller or microprocessor with A/D inputs. This transducer combines advanced micromachining techniques, thin-film metallization, and bipolar processing to provide an accurate, high level analog output signal that is proportional to the applied pressure.
Features
• 2.5% Typical Error over +10C to +60C with Auto Zero
• 6.25% Maximum Error over +10C to +60C without Auto Zero
• Ideally Suited for Microprocessor or Microcontroller-Based Systems
• Thermoplastic (PPS) Surface Mount Package
• Temperature Compensated over +10 to +60C
• Patented Silicon Shear Stress Strain Gauge
• Available in Differential and Gauge Configurations
ORDERING INFORMATION Device Name Package
Options
Case No.
# of Ports Pressure Type Device
Marking None Single Dual Gauge Differential Absolute
Small Outline Package (MPXV7002 Series)
MPXV7002GC6U Rails 482A • • MPXV7002G
MPXV7002GC6T1 Tape & Reel 482A • • MPXV7002G
MPXV7002GP Trays 1369 • • MPXV7002G
MPXV7002DP Trays 1351 • • MPXV7002DP
MPXV7002
MPXV7002
1 Operating Characteristics
Table 1. Operating Characteristics (VS = 5.0 Vdc, TA = 25°C unless otherwise noted. Decoupling circuit shown in Figure 3 required to meet specification.)
Characteristic Symbol Min Typ Max Unit
Pressure Range(1)
1. 1.0 kPa (kiloPascal) equals 0.145 psi.
POP –2.0 — 2.0 kPa
Supply Voltage(2)
2.Device is ratiometric within this specified excitation range.
VS 4.75 5.0 5.25 Vdc
Supply Current Io — — 10 mAdc
Pressure Offset(3) (10 to 60C)
@ VS = 5.0 Volts
3.Offset (Voff) is defined as the output voltage at the minimum rated pressure.
Voff 2.25 2.5 2.75 Vdc
Full Scale Output(4) (10 to 60C)
@ VS = 5.0 Volts
4.Full Scale Output (VFSO) is defined as the output voltage at the maximum or full rated pressure.
VFSO 4.25 4.5 4.75 Vdc
Full Scale Span(5) (10 to 60C)
@ VS = 5.0 Volts
5.Full Scale Span (VFSS) is defined as the algebraic difference between the output voltage at full rated pressure and the output voltage at the minimum rated pressure.
VFSS 3.5 4.0 4.5 V Vdc
Accuracy(6) (10 to 60C)
6.Accuracy (error budget) consists of the following:
Linearity: Output deviation from a straight line relationship with pressure over the specified pressure range.
Temperature Hysteresis: Output deviation at any temperature within the operating temperature range, after the temperature is cycled to and from the minimum or maximum operating temperature points, with zero differential pressure applied.
Pressure Hysteresis: Output deviation at any pressure within the specified range, when this pressure is cycled to and from the minimum or maximum rated pressure, at 25C.
TcSpan: Output deviation over the temperature range of 10 to 60C, relative to 25C.
TcOffset: Output deviation with minimum rated pressure applied, over the temperature range of 10 to 60C, relative to 25C.
Variation from Nominal: The variation from nominal values, for Offset or Full Scale Span, as a percent of VFSS, at 25C.
— — 2.5(7)
7.Auto Zero at Factory Installation: Due to the sensitivity of the MPXV7002 Series, external mechanical stresses and mounting position can affect the zero pressure output reading. Auto zero is defined as storing the zero pressure output reading and subtracting this from the device's output during normal operations. Reference AN1636 for specific information. The specified accuracy assumes a maximum temperature change of ± 5C between auto zero and measurement.
6.25 %VFSS
Sensitivity V/P — 1.0 —- V/kPa
Response Time(8)
8.Response Time is defined as the time for the incremental change in the output to go from 10% to 90% of its final value when subjected to a specified step change in pressure.
tR — 1.0 —- ms
Output Source Current at Full Scale Output IO+ — 0.1 —- mAdc
Warm-Up Time(9)
9.Warm-up Time is defined as the time required for the product to meet the specified output voltage after the Pressure has been stabilized.
— — 20 —- ms
MPXV7002
2 Maximum Ratings
Figure 1 shows a block diagram of the internal circuitry integrated on a pressure sensor chip.
Figure 1. Integrated Pressure Sensor Schematic Table 2. Maximum Ratings(1)
1.Exposure beyond the specified limits may cause permanent damage or degradation to the device.
Rating Symbol Value Unit
Maximum Pressure (P1 > P2) Pmax 75 kPa
Storage Temperature Tstg –30 to +100 C
Operating Temperature TA 10 to 60 C
Sensing
MPXV7002
3 On-Chip Temperature Compensation, Calibration and Signal Conditioning
The performance over temperature is achieved by integrating the shear-stress strain gauge, temperature compensation, calibration and signal conditioning circuitry onto a single monolithic chip.
Figure 2 illustrates the Differential or Gauge configuration in the basic chip carrier (Case 482). A gel die coat isolates the die surface and wire bonds from the environment, while allowing the pressure signal to be transmitted to the sensor diaphragm.
The MPXV7002 series pressure sensor operating characteristics, and internal reliability and qualification tests are based on use of dry air as the pressure media. Media, other than dry air, may have adverse effects on sensor performance and long-term reliability. Contact the factory for information regarding media compatibility in your application.
Figure 3 shows the recommended decoupling circuit for interfacing the integrated sensor to the A/D input of a microprocessor or microcontroller. Proper decoupling of the power supply is recommended.
Figure 4 shows the sensor output signal relative to pressure input. Typical, minimum, and maximum output curves are shown for operation over a temperature range of 10 to 60C using the decoupling circuit shown in Figure 3. The output will saturate outside of the specified pressure range.
Figure 2. Cross-Sectional Diagram SOP (not to scale)
Figure 3. Recommended Power Supply Decoupling and Output Filtering (For additional output filtering, please refer to Application Note AN1646.)
Fluoro Silicone
MPXV7002 Figure 4. Output versus Pressure Differential
4 Pressure (P1)/Vacuum (P2) Side Identification Table
Freescale designates the two sides of the pressure sensor as the Pressure (P1) side and the Vacuum (P2) side. The Pressure (P1) side is the side containing a gel die coat which protects the die from harsh media.
The Pressure (P1) side may be identified by using the following table:
5 Minimum Recommended Footprint for Surface Mounted Applications
Surface mount board layout is a critical portion of the total design. The footprint for the surface mount packages must be the correct size to ensure proper solder connection interface between the board and the package. With the correct footprint, the packages will self align when subjected to a solder reflow process. It is always recommended to design boards with a solder mask layer to avoid bridging and shorting between solder pads.
Figure 5. Small Outline Package Footprint
Part Number Case Type Pressure (P1)
Side Identifier
MPXV7002GC6U/GC6T1 482A-01 Side with Port Attached
MPXV7002GP 1369-01 Side with Port Attached
MPXV7002DP 1351-01 Side with Part Marking
Differential Pressure (kPa)
MPXV7002
MPXV7002 CASE 1351-01
ISSUE A
SMALL OUTLINE PACKAGE
MPXV7002
MPXV7002 CASE 1369-01
ISSUE B
SMALL OUTLINE PACKAGE
MPXV7002
CASE 1369-01 ISSUE B
SMALL OUTLINE PACKAGE
MPXV7002
7 Revision History
Table 1. Revision History
Revision number
Revision
date Description of changes
3 01/2015
• Updated data sheet format.
• Added Pinout.
• Updated package outline for 98ASA99303D.
Information in this document is provided solely to enable system and software implementers to use Freescale products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document.
Freescale reserves the right to make changes without further notice to any products herein. Freescale makes no warranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters that may be provided in Freescale data sheets and/or specifications can and do vary in different applications, and actual performance may vary over time. All operating parameters, including “typicals,” must be validated for each customer application by customer’s technical experts. Freescale does not convey any license under its patent rights nor the rights of others. Freescale sells products pursuant to standard terms and conditions of sale, which can be found at the following address:
http://www.reg.net/v2/webservices/Freescale/Docs/TermsandConditions.htm.
Freescale and the Freescale logo are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. All other product or service names are the property of their respective owners.
© 2015 Freescale Semiconductor, Inc. All rights reserved.
How to Reach Us:
Home Page:
www.freescale.com Web Support:
http://www.freescale.com/support
B iRon II Dataset
Juan Francisco Fuentes-Pérez
1
iRon II- Dataset V.1.0
1. Description of the device
iRon is a NACA0025 shape prototype of a chord length of 220 mm. The prototype has ten differential pressure sensors (1-10, MPXV7002) with a measuring range of ±2000 Pa and an absolute one (11– MPX5010GP) with a measuring range from 0 to 10000 Pa (10 m of water column) (Figure 1).
Figure 1. Sensor order and numbering (source: JF Fuentes-Pérez).
The sensors analog output is transmitted into two 8 channels A/D (analog to digital) converter of 16 bits (LTC1867). Due to the target controlled application temperature sensors have not been added to the current prototype. In the future temperature sensors will be added to each of the sensors.
Figure 2. Final prototype after underwater testing (source: JF Fuentes-Pérez).
Juan Francisco Fuentes-Pérez
2
2. Data
The sampling frequency is programmable; at the moment it is fixed to 200 Hz. Each data line has a time stamp (milliseconds from connection), Ps1, Ps2, Ps3, Ps4, Ps5, Ps6, Ps7, Ps8, Ps9, Ps10 and Ps11 (last correspond to absolute pressure sensor), all of them separated by commas (Figure 3).
Figure 3. Data format file from iRon II (source: JF Fuentes-Pérez).
The data from the sensor is raw from the A/D and it has to be translated into Pascal units and, in the same way, a constant offset sensor dependant has to be subtracted. For lab experiments it is recommended to record before each new run
1a dataset during steady conditions to subtract this constant offset. This file will be used to calculate the offset in each run. Figure 4 shows the dataset processing workflow to be programmed.
Figure 4. Recommended data processing workflow for the data.
3. Calibration Equations
3.1. Differential pressure sensors
1 Our experience says that one dataset in steady conditions underwater is enough, however it is highly recommended to record a new one before every new test run.
Juan Francisco Fuentes-Pérez
3
Figure 5. Pascal bit relation for differential pressure sensors
( )
Pressure (Pa)=0.0685 bits-Offset (1)
3.2. Absolute pressure sensor
Max A/D converter range = 2
16= 65536 bits (5 v)
Table 1. Test performed in the lab to ensure the correct performance of the electronics
Measured bits Water column (cm)
Pressure (kPa) V (according to dataset)
Assuming linearity (supported but previous test and the dataset):
( )
C Formlabs Tough Resin Material Data Sheet
Tough
MATERIAL DATA SHEET
FLTOTL05
Tough Resin for Rugged Prototyping
Tough Resin balances strength and compliance, making it the ideal choice for prototyping strong, functional parts and assemblies that will undergo brief periods of stress or strain.
Sturdy prototypes Interference and press fits Assemblies
$175 / L
Solvent Compatibility
Percent weight gain over 24 hours for a printed and post-cured 1 x 1 x 1 cm cube immersed in respective solvent:
Material Properties Data
METRIC1 IMPERIAL1 METHOD
Green2 Post-Cured3 Green2 Post-Cured3 Mechanical Properties
Ultimate Tensile Strength 34.7 MPa 55.7 MPa 5040 psi 8080 psi ASTM D 638-14
Tensile Modulus 1.7 GPa 2.7 GPa 239 ksi 387 ksi ASTM D 638-14
Elongation at Break 42 % 24 % 42 % 24 % ASTM D 638-14
Flexural Strength at 5% Strain 20.8 MPa 60.6 MPa 3020 psi 8790 psi ASTM D 790-15
Flexural Modulus 0.6 GPa 1.6 GPa 90.3 ksi 241 ksi ASTM D 790-15
Notched IZOD 32.6 J/m 38 J/m 0.61 ft-lbf/in 0.71 ft-lbf/in ASTM D256-10
Thermal Properties
Heat Deflection Temp. @ 1.8 MPa 32.8 °C 45.9 °C 91.1 °F 114.6 °F ASTM D 648-16
Heat Deflection Temp. @ 0.45 MPa 40.4 °C 48.5 °C 104.7 °F 119.3 °F ASTM D 648-16
Thermal Expansion (23 – 50 °C) 159.7 µm/m/°C 119.4 µm/m/°C 88.7 µin/in/°F 66.3 µin/in/°F ASTM E 831-13
1 Material properties can vary with part geometry, print orientation, print settings, and temperature.
2 Data was obtained from green parts, printed using Form 2, 100 µm, Tough settings, without additional treatments.
3 Data was obtained from parts printed using Form 2, 100 µm, Tough settings and post-cured with 2.5 mW/cm² of 405 nm LED light for 120 minutes at 60°C.
Solvent 24 hr weight gain (%) Solvent 24 hr weight gain (%)
Acetic Acid, 5 % 2.8 Hydrogen Peroxide (3 %) 2.1
Acetone sample cracked Isooctane < 1
Isopropyl Alcohol 2.1 Mineral Oil, light < 1
Bleach, ~5 % NaOCl 1.7 Mineral Oil, heavy < 1
Butyl Acetate 1.6 Salt Water (3.5 % NaCl) 1.5
Diesel < 1 Sodium hydroxide (0.025 %, pH = 10) 1.5
Diethyl glycol monomethyl ether 6.6 Water 1.6
Hydrolic Oil < 1 Xylene < 1
Skydrol 5 1.2 Strong Acid (HCI Conc) distorted