Katsuaki Morita

Temperature-Cancelled Anodized-Aluminum Pressure Sensitive Paint for Hypersonic Wind Tunnel Application

Temperature-cancelled anodized-aluminum pressure-sensitive paint (AAPSP) is applied in The Mach 7.1 Hypersonic and High Enthalpy Wind Tunnel at The University of Tokyo, Kashiwa Campus. Our temperature-cancelled AAPSP uses an intermediate range of two peaks of pyrenesulfonic acid. The surface temperature increase due to aerodynamic heating is captured by using anodized-aluminum temperature-sensitive paint (AA-TSP). The temperature is increased up to 130 °C after placing the model in the test section for 9 s. The temperature-cancellation method as well as pressure and temperature calibrations are also included in this paper.

Hydrophobic Coating Study for Anti-icing Aircraft

Submitted for the DFD10 Meeting of The American Physical Society Hydrophobic coating study for anti-icing aircraft KATSUAKI MORITA, University of Tokyo, AKIHITO AOKI, AKIHISA KONNO, Kogakuin University, HIROTAKA SAKAUE, JAXA — Anti-icing or deicing of an aircraft is necessary for a safe flight operation. Mechanical processes, such as heating and deicer boot, are widely used. Deicing fluids, such as ethylene glycol type, are used to coat the aircraft. However, these should be coated every time before the take-off, since the fluids come off from the aircraft while cruising. We study a hydrophobic coating as a anti-icing for an aircraft. It is designed to coat the aircraft without removal. Since a hydrophobic coating prevents water by reducing the surface energy, it would be another way to prevent ice on the aircraft. We provide a temperaturecontrolled room, which can control its temperature at an icing condition (-10 to 0 degrees C). The contact angle is tested for various hydrophobic coatings. A water jet impingement on a hydrophobic-coated plate is included. The jet freezes under the icing condition. Qualitative comparison among various hydrophobic coatings as anti-icing is discussed. Katsuaki Morita University of Tokyo Date submitted: 09 Aug 2010 Electronic form version 1.4

Development of Luminophore-Pendant Temperature-Sensitive Paint and its Application to Pressure-Sensitive Paint for Aerodynamic Measurements

In this paper, current status of the development of luminophore-pendant temperature-sensitive paint of poly[l-(trimetylsilyl)phenyl-2-phenylacetylene] (PTMST) is discussed. PTMST uses poly(l-trimethylsilyl-l-propyne) (PTMSP) based polymer, which is known as one of the highest gas permeable polymers. Because of its high gas permeability and single luminescent compound, we can expect fast response of PTMST to the change in temperature and pressure of the test gas. We can also create PTMST-based two-color PSP for temperature-compensated pressure sensor by simply mixing pressure-sensitive luminophore in PTMST. In this paper, we mix platinum tetrakis (pentafluorophenyl) porphyrin (PtTFPP) as a pressure-sensitive luminophore to create PTMST-based two-color PSP (PtTFPP-PTMST). Spectral analysis shows that PtTFPP-PTMST provides temperature sensitive peak of PTMST (around 540 nm) and pressure sensitive peak of PtTFPP (around 650 nm), which can be separated by band-pass filters. We have calibrated PTMST from 100 K to 373 K as well as PtTFPP-PTMST from 120 K to 333 K to study the static characteristics of these sensors. PTMST provides the temperature sensitivity over the calibrated range, giving the maximum value of 2.72%/K at 100 K. PTMST itself is almost pressure independent. Pressure sensitivity of PtTFPP-PTMST is 0.26%/kPa at 293 K. PtTFPP-PTMST shows pressure sensitivity of 0.66%/kPa even at cryogenic temperature of 120 K. The unsteady characteristic of PtTFPP-PTMST is determined using a step response to a pressure change caused by a shock tube. The response time of PtTFPP-PTMST is on the order of milliseconds. A demonstration of PTMST at cryogenic measurement is shown by transition detection of PTMST-coated NACA64A012 model in JAXA 0.1m Transonic Cryogenic Wind Tunnel. PTMST detects a natural transition as well as a forced transition induced by a roughness at the leading edge at Mach 0.4, total temperature 200 K, and total pressure 120 kPa.

Characterization method of hydrophobic anti-icing coatings.

For anti-icing, supercooled water should be removed before frozen onto the contact surface. We use a hydrophobic coating for anti-icing and introduce the static- and dynamic-evaluation methods. The methods describe the contact surface between the hydrophobic surface and a supercooled-water droplet. The former is based on the contact angle, and the latter is based on the sliding angle. The temperature factor is included in these models to evaluate the hydrophobic coating under the supercooled conditions. Four hydrophobic coatings are experimentally evaluated based on the static- and dynamic evaluation methods: C1-C3 (commercial fluorocarbon coatings), and Jaxa coating (original fluorocarbon coating). These are evaluated under the supercooled conditions of -10 to 0 °C. The static-evaluation shows variations in the temperature. However, change in the contact angle by the temperature is relatively small compared to that of the sliding angle for the dynamic evaluation. Only C3 and Jaxa coatings are tolerant to the sliding angle under the supercooled conditions tested. The dynamic evaluation shows that even if the coating is hydrophobic, the dynamic evaluation should be included to understand the characteristic of removal for a supercooled-water droplet.

Study of Icing Process using Dual-Luminescence Imaging for Aircraft-Icing Prevention

A hydrophobic coating has been paid attention as an ice-prevention coating on an aircraft surface. The icing process of a supercooled water droplet on the coating surface will give great insights into the further development of the ice-prevention coating. To understand the icing process, the time-resolved temperature distributions of the droplet will be a key factor. A dual-luminescent imaging is introduced and applied to capture the temperature distributions of the droplet on a hydrophobic surface. This paper describes the temperaturecapturing method of the dual-luminescence imaging, the characterizations of the imaging system, and the temperature measurements. The temperature measurements include the time-resolved temperature distributions of the droplet under static and dynamic conditions.

Development of Spray-able Superhydrophobic Pressure-Sensitive Paint for Unsteady Aerodynamic Applications

We introduce a superhydrophobic pressure-sensitive paint (superhydrophobic PSP) that 9 provides the contact angle over 150o. It uses a teflon-based particle that can be sprayed onto 10 a testing model. This PSP is aimed for the aerodynamic measurements where the test gas 11 varies the humidity. Because the pressure is related to the luminescent output from a PSP, 12 other gaseous parameters, such as humidity, should be cancelled or removed. The developed 13 PSP can maintain its luminescent output within 2% variation above the pressure of 40 kPa 14 under the relative humidity of 60%. Even if the humidity is increased at 80%, the 15 luminescent output can be maintained within 6% variation. The contact angle over 150o can 16 be provided if the PSP thickness is over 2 to 5 m. The pressure sensitivity is 0.9 %/kPa, 17 which is independent of the humidity. Because of its porous structure, this PSP will provide 18 a fast response time that can be applied for unsteady aerodynamic measurements. At the 19 current stage with the PSP thickness of 25 m, the response time is 200 ms. 20

Development and Application of Dual-Luminescence Imaging for Capturing Supercooled-Water Droplet under Icing Conditions

We introduce a dual-luminescent imaging to capture the temperature distribution of 9 supercooled-water droplets for understanding the icing process. Two luminescent probes of 10 coumarin and rhodamine derivatives are used to obtain the temperature-independent and 11 temperature-dependent images. Both images are simultaneously acquired by a high-speed 12 color camera. The temperature calibration of the developed system shows the temperature 13 sensitivity of -5.4 %/°C. This system captures the time-resolved staticand dynamic-icing 14 processes of a supercooled-water droplet under the icing conditions. 15

Flow Visualization over Cylindrical Surfaces with Hydrophobic and Hydrophilic Coatings

C 2 〇 5 疎水性•親水性表面を持つ円柱模型近傍の流れの可視化 守 田 克 彰 Q 、 坂 上 博 隆 ( 宇 宙 航 空 研 究 開 発 機 構 ) Flow Visualization over Cylindrical Surfaces with Hydrophobic and Hydrophilic Coatings Katsuaki MORITA and Hirotaka SAKAUE ABSTRACT Effect of hydrophobic and hydrophilic coating on Karman vortex formation is discussed. The flow is visualized by a hydrogen bubble technique in a circular water tunnel. Karman vortex sheet is captured at a camera frame rate of 200 Hz. I t is shown that, at Reynolds number of 50, hydrophobic coating delayed a formation of Karman vortex sheet.