The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform

Keisuke Asai - One of the best experts on this subject based on the ideXlab platform.

  • frequency response of Pressure Sensitive Paints under low Pressure conditions
    Sensors, 2021
    Co-Authors: Miku Kasai, Daisuke Sasaki, Takayuki Nagata, Taku Nonomura, Keisuke Asai
    Abstract:

    The characteristics of fast-response Pressure-Sensitive Paints (PSPs) in low-Pressure conditions were evaluated. Three representative porous binders were investigated: polymer-ceramic PSP (PC-PSP), anodized-aluminum PSP (AA-PSP), and thin-layer chromatography PSP (TLC-PSP). For each PSP, two types of luminophores, Pt(II) meso-tetra (pentafluorophenyl) porphine (PtTFPP) and tris(bathophenanthroline) ruthenium dichloride (Ru(dpp)3), were used as sensor molecules. Pressure sensitivities, temperature sensitivities, and photodegradation rates were measured and evaluated using a Pressure chamber. The effect of ambient Pressure on the frequency response was investigated using an acoustic resonance tube. The diffusivity coefficients of PSPs were estimated from the measured frequency response and luminescent lifetime, and the governing factor of the frequency response under low-Pressure conditions was identified. The results of static calibration show that PC-PSP/PtTFPP, AA-PSP/Ru(dpp)3, and TLC-PSP/PtTFPP have high Pressure sensitivities that exceed 4%/kPa under low-Pressure conditions and that temperature sensitivity and photodegradation rates become lower as the ambient Pressure decreases. Dynamic calibration results show that the dynamic characteristics of PSPs with PtTFPP are dependent on the ambient Pressure, whereas those of PSPs with Ru(dpp)3 are not influenced by the ambient Pressure. This observation indicates that the governing factor in the frequency response under low-Pressure conditions is the lifetime for PC-PSP and TLC-PSP, whereas the governing factor for AA-PSP is diffusion.

  • polymer ceramic Pressure Sensitive paint with reduced roughness for unsteady measurement in transonic flow
    AIAA Journal, 2018
    Co-Authors: Yosuke Sugioka, Keisuke Asai, Kazuyuki Nakakita, Daiju Numata, Shunsuke Koike, Tsutomu Nakajima
    Abstract:

    Polymer/ceramic Pressure-Sensitive Paints with reduced surface roughness were developed for measuring unsteady Pressure fields in transonic flow. Four types of polymer/ceramic Pressure-Sensitive pa...

  • characterization of frequency response of Pressure Sensitive Paints
    AIAA Journal, 2017
    Co-Authors: Tamao Sugimoto, Hiroki Nagai, Yosuke Sugioka, Daiju Numata, Keisuke Asai
    Abstract:

    In this study, the frequency characteristics of fast-responding Pressure-Sensitive Paints(PSP) were evaluated by using a device based on an acoustic tube. The gain and phase characteristics of two different types of fast-responding PSP, Polymer-Ceramic PSP and Anodized-Aluminum PSP, were measured over the frequency range from 0.15 to 10 kHz and their dependence on binder, luminophore and temperature were investigated. From the measured frequency characteristics, the transfer functions were evaluated and the factors governing the time response of each PSP were estimated. The results of this study have suggested that luminophore molecules are distributed near the surface of PC-PSP and on the other hand are adsorbed inside the pores of AA-PSP.

  • ultrafast response anodized aluminum Pressure Sensitive Paints for unsteady flow measurement
    AIAA Journal, 2017
    Co-Authors: Daiju Numata, Hiroki Nagai, Shota Fujii, Keisuke Asai
    Abstract:

    To apply Pressure-Sensitive paint (PSP) to unsteady shock-wave phenomena such as shock–obstacle interactions in shock-tube experiments, anodized-aluminum PSP (AA-PSP) with ultrafast response was fabricated and its response time to a step Pressure change was evaluated by using a shock tube. Phosphoric acid was used as electrolyte in the anodization process, and the anodic alumina with pore diameter as large as 160 nm was successfully fabricated. This improved AA-PSP achieved a response with the time constant of 0.35  μs. This AA-PSP was applied to interactions of a moving shock wave with a circular cylinder. The results show that the improved AA-PSP can visualize the shock reflections and the shock diffractions with the ever-highest spatial and temporal resolution.

  • development of ultrafast response anodized aluminum Pressure Sensitive Paints
    51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013, 2013
    Co-Authors: Shota Fujii, Daiju Numata, Hiroki Nagai, Keisuke Asai
    Abstract:

    In order to apply Pressure-Sensitive Paint (PSP) to unsteady shock-wave phenomena, Anodized-Aluminum PSP (AA-PSP) with ultrafast response was fabricated and its response time to a step Pressure change was evaluated by using a shock tube. Phosphoric acid was used as electrolyte in anodization and the anodic alumina with pore diameter as large as 160 nm was successfully fabricated. The improved AA-PSP achieved a response with the time constant of 0.35 s. This is the fastest PSP ever reported. We applied this AA-PSP to interactions of a moving shock wave with a circular cylinder. The results show that the improved AA-PSP can visualize the shock reflections and the shock diffractions with the ever-highest spatial and temporal resolution. Nomenclature Ai = Stern-Volmer coefficients d = pore diameter, nm Deff = effective diffusion coefficient, m 2 s -1

Konstantinos Kontis - One of the best experts on this subject based on the ideXlab platform.

  • static and wind on performance of polymer based Pressure Sensitive Paints using platinum and ruthenium as the luminophore
    Sensors, 2016
    Co-Authors: Konstantinos Kontis
    Abstract:

    An experimental study has been conducted to investigate the static and wind-on performance of two in-house-developed polymer-based Pressure-Sensitive Paints. Platinum tetrakis (pentafluorophenyl) porphyrin and tris-bathophenanthroline ruthenium II are used as the luminophores of these two polymer-based Pressure-Sensitive Paints. The Pressure and temperature sensitivity and the photo-degradation rate of these two Pressure-Sensitive Paints have been investigated. In the wind tunnel test, it was observed that the normalised intensity ratio of both polymer-based Pressure-Sensitive Paints being studied decreases with increasing the number of wind tunnel runs. The exact reason that leads to the occurrence of this phenomenon is unclear, but it is deduced that the luminophore is either removed or deactivated by the incoming flow during a wind tunnel test.

  • global unsteady Pressure Sensitive paint measurements of a moving shock wave using thin layer chromatography
    Measurement, 2010
    Co-Authors: N Gongoraorozco, H Zarebehtash, Konstantinos Kontis
    Abstract:

    Unsteady Pressure measurements using Pressure-Sensitive Paints (PSP) requires a very porous substrate to carry the luminophore molecules. The porosity increases the probability of oxygen quenching and leads to a faster response time. Obtaining these porous material to apply the PSP can be a tedious process requiring specialised equipment and strong chemical background. The focus of the current study is to demonstrate the feasibility of using thin-layer chromatography (TLC) plates along with a simple paint formulation, with Ruthenium as the luminophore and Dichloromethane as the solvent. The TLC–PSP results show good correlation with the schlieren images, the shock front deceleration caused with the interaction of the grooves on the bottom wall. The global Pressure measurements are also in agreement with point Pressure measurements located at the centreline of the test section.

  • optical altitude sensor based on Pressure Sensitive Paints psp
    International Journal of Aerospace Innovations, 2009
    Co-Authors: A Khalid, Konstantinos Kontis
    Abstract:

    The altitude is one of the most important measurements in aviation. Since atmospheric Pressure decreases with increasing altitude, static Pressure readings can be indicative of altitude. The purpose of this paper is to present a novel fibre optic based system that incorporates PSP at the tips to first determine Pressure and temperature, and later used to determine altitude. The use of PSP to measure Pressure is well established and has been employed in a wide range of applications. PSP relies on the quenching behaviour by oxygen, which can be related to Pressure. Temperature can also be simultaneously determined. In the presented system, the fibre is used to deliver illumination light to the PSP and also collect any subsequent emissions via total internal reflection. The porous reflective layer ensures that PSP luminophores are effectively illuminated with their subsequent emissions returned back into the fibre. The system was demonstrated in the Manchester environmental chamber.

  • effects of filters on the performance and characteristics of Pressure Sensitive Paints
    Measurement Science and Technology, 2009
    Co-Authors: N Gongoraorozco, H Zarebehtash, Konstantinos Kontis
    Abstract:

    The current study investigates the effect of four different filter combinations on the Pressure sensitivity, signal level and temperature sensitivity of Pressure-Sensitive paint (PSP) samples in an a priori calibration. Two different PSP formulations developed at the Aero-Physics Laboratory are studied, one using hydrochloric acid (PSP1-HCl) and the other acetone (PSP2-Ace). Both are incorporated in a sol–gel solution. The results show that the effect of choosing different bandwidths, central wavelengths and transmissions of the filters for the emitted and excitation wavelengths can have a significant impact on the behaviour of PSP, luminescent signal level, Pressure and temperature sensitivity, and also eliminate the undesired wavelengths which can affect the final results.

  • application of Pressure Sensitive Paints in high speed flows
    In: 26th International Symposium on Shock Waves: 26th International Symposium on Shock Waves; 2007. p. 7., 2009
    Co-Authors: H Zarebehtash, N Gongora, C Lada, Diamantis Kounadis, Konstantinos Kontis
    Abstract:

    Pressure-Sensitive paint (PSP) has become a useful tool to augment conventional Pressure taps in measuring the surface Pressure distribution of aerodynamic components (Mosharov et al. [1]). PSP offers the advantage of nonintrusive global mapping of the surface Pressure.

Walter Beck - One of the best experts on this subject based on the ideXlab platform.

  • measurement of an oscillating shock wave in a transonic flow using two different Pressure Sensitive Paints ru based on anodized aluminum vs pt based with screen layer
    2018 Aerodynamic Measurement Technology and Ground Testing Conference, 2018
    Co-Authors: Walter Beck, Christian Klein, Ulrich Henne, Marieclaire Merienne, Yves Le Sant, Pascal Molton
    Abstract:

    The performance of two different PSP used at DLR and ONERA is compared by carrying out bench mark testing using the oft-studied configuration of an oscillating shock wave (up to 100 Hz) on a bump in the Mach 1.4 flow of the ONERA S8Ch wind tunnel. The shock is made to oscillate by rotating a cam with elliptical cross section, placed at a further downstream position, at frequencies of 15, 30 and 50 Hz. Both paint types are well known and much has been published on their use: the ONERA PSP is a Ruthenium complex Ru(dpp)_3Cl_2 placed as a thin layer on an anodized aluminum substrate, while the DLR PSP is a Platinum complex PtTFPP on a base coating containing TiO_2 particles. S8 run conditions were held constant, and separate test run series were carried out with each paint. Instationary calibration was also carried out using a special test rig. Fourier analyses of the PSP results in S8 enabled a semi-quantitative comparison of the time response of both Paints. This is the first published attempt (to the authors’ knowledge) of carrying out a side-by-side comparison of the characteristics of these two Paints on such a flow configuration in a wind tunnel. Particular emphasis is placed on their handling properties and, above all, their time responses.

  • benchmark testing of onera and dlr Pressure Sensitive Paints for unsteady instationary flows
    2016
    Co-Authors: Marieclaire Merienne, Christian Klein, Ulrich Henne, Yves Le Sant, Pascal Molton, Walter Beck, Yves Carpels, Werner Sachs
    Abstract:

    Aim: Some years ago, in the framework of the Motar Cooperation Agreement between ONERA and DLR, it had been agreed to carry out comparison testing of the two instationary PSP methods on a common test configuration with an unsteady flow produced in a suitable wind tunnel. The results from this comparison would form the basis for a benchmarking of the two different approaches, leading to an aid in decision-making as to which method is better suited for a particular application. / Test configuration: For many years there has been interest at ONERA on the (quasi) two-dimensional unsteady transonic flow in a channel with strong interactions between an oscillating shock and a separated boundary layer: various diagnostic methods were used in measurements on their S8Ch transonic wind tunnel at ONERA Meudon (Schlieren, Pressure sensors, PIV, LDV), including also PSP with Ru/AA paint (uPSP). Flow separation of the boundary layer is produced over a convex contour profile (a bump) on the floor of the tunnel, with the subsequent flow acceleration leading to formation of a downstream shock wave. The sectional area of a second throat, situated downstream of the bump, is varied periodically (ca. 15 Hz or higher) by rotation of an elliptical rod (cam) placed downstream of the throat position, leading to forced upstream Pressure fluctuations and hence an oscillation (movement in flow direction) in the shock position. The resulting Pressure fluctuations on the bump can then be measured with the help of Pressure sensors (Kulite) fixed in the floor, and also with PSP coated on the floor. / Procedure/Approach: The floor can also be coated with the DLR iPSP paint. As with ONERA, there exists sufficient optical access for placement of the DLR excitation LEDs and cameras adjacent to or above the test section. PSP measurements were then be carried out with a new set of measurements using both ONERA and DLR Paints, consecutively. / Results: Pressure measurements with Kulite and iPSP/uPSP are compared. Phase correlation is good, but there remain some differences in amplitude for both Paints. Static and instationary calibration were carried out on samples of both Paints; the latter showed no phase loss up to 120 Hz, although the amplitude with iPSP dropped due to surface heating by the LED over time. Fourier analyses of Kulite and PSP showed good agreement. A table was compiled with a summary of characteristics for both Paints: there is no “better” paint, since the choice is governed mainly by desired application.

  • application of temperature and Pressure Sensitive Paints to dlr hypersonic facilities lessons learned
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Walter Beck, Christian Klein, Ulrich Henne, Werner Sachs, Jan Martinez Schramm, Alexander Wagner, Klaus Hannemann, Thomas Gawehn, Ali Gulhan
    Abstract:

    PSP and TSP measurements have been carried out on the following DLR facilities: small test shock tube, High Enthalpy Shock Tunnel (both in Gottingen) and the Hypersonic Wind Tunnel (in Cologne). Based on the results from these measurements, various challenges and problem areas could be identified: the role played by these in hindering a quantitative application of PSP/TSP to the facilities is discussed, and ways and means are presented for either overcoming them or at least ameliorating their influence.

  • benchmark testing in the s8 wind tunnel of onera and dlr Pressure Sensitive Paints for measurements in unsteady instationary flows
    2015
    Co-Authors: Marieclaire Merienne, Christian Klein, Yves Le Sant, Pascal Molton, Serge Ost, Giles Losfeld, Walter Beck, Ulrich Henne
    Abstract:

    Measurements using ONERA (uPSP) and DLR (iPSP) Pressure Sensitive Paints of the shock/boundary layer interaction phenomenon were carried out in the ONERA wind tunnel S8 in order to obtain a benchmark testing of these two Paints. uPSP and iPSP images (as films) were shown and compared with time-resolved Schlieren measurements.

Bharathibai J Basu - One of the best experts on this subject based on the ideXlab platform.

  • a novel pyrene based binary Pressure Sensitive paint with low temperature coefficient and improved stability
    Sensors and Actuators B-chemical, 2009
    Co-Authors: Bharathibai J Basu, N Vasantharajan, Channa Raju
    Abstract:

    Pyrene-based Pressure Sensitive Paints (PSP) have certain advantages due to their high Pressure sensitivity and low temperature coefficient but their major drawback is the paint degradation under wind tunnel conditions. This is due to the loss of pyrene as a result of diffusion and sublimation from the coating. We have developed a novel stable binary PSP formulation in which pyrene is covalently bonded to the polymer binder so that paint degradation is prevented. The coating thus obtained is a siloxane-based hybrid organic-inorganic material. The Pressure Sensitive paint also contains an additional reference luminophore, which is inSensitive to Pressure but Sensitive to intensity variations on the model surface. The second luminophore is incorporated in the paint to correct for the excitation intensity variations during the wind tunnel experiment. The temperature coefficient of second luminophore exactly cancels the temperature coefficient of the Pressure Sensitive luminophore, thereby resulting in a binary paint with negligible temperature sensitivity.

  • study of the mechanism of degradation of pyrene based Pressure Sensitive Paints
    Sensors and Actuators B-chemical, 2003
    Co-Authors: Bharathibai J Basu, C Anandan, K S Rajam
    Abstract:

    Even though pyrene-based Pressure Sensitive Paints have some special advantages like high quantum efficiency, good Pressure sensitivity and low temperature sensitivity, these Paints exhibit steady degradation of the fluorescent intensity after each wind tunnel test. It has been reported that pyrene-based Paints degrade because pyrene has a tendency to evaporate. It is necessary to understand the mechanism of degradation of pyrene-based Paints in order to find a solution to this problem. Thermal aging tests and UV exposure tests of the paint specimens are carried out to study the effect of experimental parameters like temperature, Pressure and UV exposure on the paint stability. This study has shown that the paint degradation in wind tunnel is mainly due to diffusion and evaporation of pyrene. The effect of pyrene concentration in the paint and the thickness of the active layer on the paint stability were also studied. © 2003 Elsevier B.V. All rights reserved.

Ulrich Henne - One of the best experts on this subject based on the ideXlab platform.

  • measurement of an oscillating shock wave in a transonic flow using two different Pressure Sensitive Paints ru based on anodized aluminum vs pt based with screen layer
    2018 Aerodynamic Measurement Technology and Ground Testing Conference, 2018
    Co-Authors: Walter Beck, Christian Klein, Ulrich Henne, Marieclaire Merienne, Yves Le Sant, Pascal Molton
    Abstract:

    The performance of two different PSP used at DLR and ONERA is compared by carrying out bench mark testing using the oft-studied configuration of an oscillating shock wave (up to 100 Hz) on a bump in the Mach 1.4 flow of the ONERA S8Ch wind tunnel. The shock is made to oscillate by rotating a cam with elliptical cross section, placed at a further downstream position, at frequencies of 15, 30 and 50 Hz. Both paint types are well known and much has been published on their use: the ONERA PSP is a Ruthenium complex Ru(dpp)_3Cl_2 placed as a thin layer on an anodized aluminum substrate, while the DLR PSP is a Platinum complex PtTFPP on a base coating containing TiO_2 particles. S8 run conditions were held constant, and separate test run series were carried out with each paint. Instationary calibration was also carried out using a special test rig. Fourier analyses of the PSP results in S8 enabled a semi-quantitative comparison of the time response of both Paints. This is the first published attempt (to the authors’ knowledge) of carrying out a side-by-side comparison of the characteristics of these two Paints on such a flow configuration in a wind tunnel. Particular emphasis is placed on their handling properties and, above all, their time responses.

  • benchmark testing of onera and dlr Pressure Sensitive Paints for unsteady instationary flows
    2016
    Co-Authors: Marieclaire Merienne, Christian Klein, Ulrich Henne, Yves Le Sant, Pascal Molton, Walter Beck, Yves Carpels, Werner Sachs
    Abstract:

    Aim: Some years ago, in the framework of the Motar Cooperation Agreement between ONERA and DLR, it had been agreed to carry out comparison testing of the two instationary PSP methods on a common test configuration with an unsteady flow produced in a suitable wind tunnel. The results from this comparison would form the basis for a benchmarking of the two different approaches, leading to an aid in decision-making as to which method is better suited for a particular application. / Test configuration: For many years there has been interest at ONERA on the (quasi) two-dimensional unsteady transonic flow in a channel with strong interactions between an oscillating shock and a separated boundary layer: various diagnostic methods were used in measurements on their S8Ch transonic wind tunnel at ONERA Meudon (Schlieren, Pressure sensors, PIV, LDV), including also PSP with Ru/AA paint (uPSP). Flow separation of the boundary layer is produced over a convex contour profile (a bump) on the floor of the tunnel, with the subsequent flow acceleration leading to formation of a downstream shock wave. The sectional area of a second throat, situated downstream of the bump, is varied periodically (ca. 15 Hz or higher) by rotation of an elliptical rod (cam) placed downstream of the throat position, leading to forced upstream Pressure fluctuations and hence an oscillation (movement in flow direction) in the shock position. The resulting Pressure fluctuations on the bump can then be measured with the help of Pressure sensors (Kulite) fixed in the floor, and also with PSP coated on the floor. / Procedure/Approach: The floor can also be coated with the DLR iPSP paint. As with ONERA, there exists sufficient optical access for placement of the DLR excitation LEDs and cameras adjacent to or above the test section. PSP measurements were then be carried out with a new set of measurements using both ONERA and DLR Paints, consecutively. / Results: Pressure measurements with Kulite and iPSP/uPSP are compared. Phase correlation is good, but there remain some differences in amplitude for both Paints. Static and instationary calibration were carried out on samples of both Paints; the latter showed no phase loss up to 120 Hz, although the amplitude with iPSP dropped due to surface heating by the LED over time. Fourier analyses of Kulite and PSP showed good agreement. A table was compiled with a summary of characteristics for both Paints: there is no “better” paint, since the choice is governed mainly by desired application.

  • application of temperature and Pressure Sensitive Paints to dlr hypersonic facilities lessons learned
    53rd AIAA Aerospace Sciences Meeting, 2015
    Co-Authors: Walter Beck, Christian Klein, Ulrich Henne, Werner Sachs, Jan Martinez Schramm, Alexander Wagner, Klaus Hannemann, Thomas Gawehn, Ali Gulhan
    Abstract:

    PSP and TSP measurements have been carried out on the following DLR facilities: small test shock tube, High Enthalpy Shock Tunnel (both in Gottingen) and the Hypersonic Wind Tunnel (in Cologne). Based on the results from these measurements, various challenges and problem areas could be identified: the role played by these in hindering a quantitative application of PSP/TSP to the facilities is discussed, and ways and means are presented for either overcoming them or at least ameliorating their influence.

  • benchmark testing in the s8 wind tunnel of onera and dlr Pressure Sensitive Paints for measurements in unsteady instationary flows
    2015
    Co-Authors: Marieclaire Merienne, Christian Klein, Yves Le Sant, Pascal Molton, Serge Ost, Giles Losfeld, Walter Beck, Ulrich Henne
    Abstract:

    Measurements using ONERA (uPSP) and DLR (iPSP) Pressure Sensitive Paints of the shock/boundary layer interaction phenomenon were carried out in the ONERA wind tunnel S8 in order to obtain a benchmark testing of these two Paints. uPSP and iPSP images (as films) were shown and compared with time-resolved Schlieren measurements.

  • Pressure Sensitive Paints and Temperature Sensitive Paints in Quantitative Wind Tunnel Studies
    2005
    Co-Authors: Rolf Engler, Christian Klein, Uwe Fey, Ulrich Henne, Werner Sachs
    Abstract:

    The Pressure Sensitive paint (PSP) intensity and lifetime system is an optical measurement technique to investigate absolute Pressure fields on model surfaces for basic research in laboratories, industrial wind tunnels or high speed rotating turbo machines. Detailed qualitative and quantitative information and understanding of flow phenomena can be obtained in speed ranges from U∞ = 20 m/s up to Ma = 5.0. A number of projects of industrial interest has been investigated in different wind tunnels covering low speed, transonic, trisonic and cryogenic facilities. The influence of the main error sources for the components of the PSP system have been checked. Comparison of experimental Pressure fields obtained by means of PSP and the results of numerical calculations have been carried out. Different wind tunnel models ranging from basic configurations such as a cropped delta wing to a complex half model of a large propeller-driven transport aircraft with all flaps, rudders and shrouds, and rotating or oscillating models as well as Reynolds number effects on models have been investigated.