Non-intrusive Measurement Technique Research Articles

Comparison of Minimum Detectable Crack Size in a Geared System From Three Different Vibration Transducer Types

Acoustic and vibration signals contain distinctive patterns useful for detecting defects in machinery. A number of signal processing strategies have been proposed for detecting and quantifying incipient defects in gears. Nonintrusive measurement techniques like those based on laser Doppler vibrometry (LDV) and microphones need to be studied in order to help users in selecting the appropriate transducer according to the application. This article presents an experimental design to determine, as a novel contribution, the minimum detectable crack size in a geared system comparing three different transducers: a microphone, an accelerometer, and an LDV. The comparison intends to discriminate the three transducers with respect to its early detection capability. Experiments were conducted in a closed loop torque test rig for several torque levels and speeds. Experimental factorial design was used to determine the main effects and their interactions in the detection process. The well-known Hilbert and wavelet transforms have been used as signal processing technique. Their advantages in the detection of incipient defects are highlighted in this article. The results indicate that the acoustic signal stands out as the method that first detects an incipient progressive crack in gears (it detected 1.3-mm-long cracks), although, as a drawback, the results obtained using the microphone signal are more sensitive to speed and torque. The second place was for LDV with 1.8-mm crack detection, and the third place for the accelerometer with 2.3-mm crack detection.

Droplet collisions and interaction with the turbulent flow within a two-phase wind tunnel

Experiments in wind tunnels concerning meteorological issues are not very frequent in the literature. However, such experiments might be essential, for instance for a careful investigation of droplet-droplet interactions in turbulent flows. This issue is crucial for many configurations, in particular to understand warm rain initiation. It is clearly impossible to completely reproduce cloud turbulence within a wind tunnel due to the enormous length scales involved. Nevertheless, it is not necessary to recover the whole spectrum in order to quantify droplet interactions. It is sufficient for this purpose to account correctly for the relevant properties only. In the present paper, these properties and a methodology for setting those in a two-phase wind tunnel are first described. In particular, droplet size and number density, velocities, turbulent kinetic energy, k, and its dissipation rate, ɛ, are suitably reproduced, as demonstrated by non-intrusive measurement techniques. A complete experimental characterization of the air and droplet properties is freely available in a database accessible at http://www.ovgu.de/isut/lss/metstroem. Finally, quantifications of droplet collision rates and comparisons with theoretical predictions are presented, showing that measured collision rates are higher, typically by a factor of 2 to 5. These results demonstrate that model modifications are needed to estimate correctly droplet collision probabilities in turbulent flows

A fast multi-resolution approach to tomographic PIV

Tomographic particle image velocimetry (Tomo-PIV) is a recently developed three-component, three-dimensional anemometric non-intrusive measurement technique, based on an optical tomographic reconstruction applied to simultaneously recorded images of the distribution of light intensity scattered by seeding particles immersed into the flow. Nowadays, the reconstruction process is carried out mainly by iterative algebraic reconstruction techniques, well suited to handle the problem of limited number of views, but computationally intensive and memory demanding. The adoption of the multiplicative algebraic reconstruction technique (MART) has become more and more accepted. In the present work, a novel multi-resolution approach is proposed, relying on the adoption of a coarser grid in the first step of the reconstruction to obtain a fast estimation of a reliable and accurate first guess. A performance assessment, carried out on three-dimensional computer-generated distributions of particles, shows a substantial acceleration of the reconstruction process for all the tested seeding densities with respect to the standard method based on 5 MART iterations; a relevant reduction in the memory storage is also achieved. Furthermore, a slight accuracy improvement is noticed. A modified version, improved by a multiplicative line of sight estimation of the first guess on the compressed configuration, is also tested, exhibiting a further remarkable decrease in both memory storage and computational effort, mostly at the lowest tested seeding densities, while retaining the same performances in terms of accuracy.

Measuring Client-Perceived Pageview Response Time of Internet Services

As e-commerce services are exponentially growing, businesses need quantitative estimates of client-perceived response times to continuously improve the quality of their services. Current server-side nonintrusive measurement techniques are limited to nonsecured HTTP traffic. In this paper, we present the design and evaluation a monitor, namely sMonitor, which is able to measure client-perceived response times for both HTTP and HTTPS traffic. At the heart of sMonitor is a novel size-based analysis method that parses live packets to delimit different webpages and to infer their response times. The method is based on the observation that most HTTP(S)-compatible browsers send significantly larger requests for container objects than those for embedded objects. sMonitor is designed to operate accurately in the presence of complicated browser behaviors, such as parallel downloading of multiple webpages and HTTP pipelining, as well as packet losses and delays. It requires only to passively collect network traffic in and out of the monitored secured services. We conduct comprehensive experiments across a wide range of operating conditions using live secured Internet services, on the PlanetLab, and on controlled networks. The experimental results demonstrate that sMonitor is able to control the estimation error within 6.7 percent, in comparison with the actual measured time at the client side.

Investigation of bubble behavior in fluidized beds with and without immersed horizontal tubes using a digital image analysis technique

Bubble characteristics such as shape, size, number and motion control the hydrodynamics and therefore heat transfer and chemical conversion in fluidized bed reactors. Thus understanding these characteristics is very important for the design and scale-up of fluidized beds. In this work a digital image analysis technique was developed to study the bubble behavior of two-dimensional bubbling beds with and without immersed horizontal tubes. Digital image analysis is a non-intrusive measurement technique which can simultaneously provide a great quantity of information without interfering with flow dynamics. The technique developed and implemented in this study allowed for the simultaneous measurement of various bubble properties, such as bubble diameter, rise velocity, aspect ratio and shape factor. A robust in-house code was developed to fully automate the image acquisition and data processing procedure. The experimental results obtained were validated and found to be in good agreement with available literature correlations. Moreover, based on the experimental results obtained new correlations for bubble growth and rise velocity as a function of bed height above the distributor were proposed. The models were in good agreement with the experimental data for a wide range of superficial velocities and particle sizes.

Numerical and experimental study on multiple-spout fluidized beds

In this paper we study the effect of multiple spouts on the bed dynamics in a pseudo-2D triple-spout fluidized bed, employing the discrete particle model (DPM) and non-intrusive measurement techniques such as particle image velocimetry (PIV) and positron emission particle tracking (PEPT). A flow regime map was constructed, revealing new regimes that were not reported so far. The multiple-interacting-spouts regime (C) has been studied in detail for a double- and triple-spout fluidized bed, where the corresponding fluidization regime for a single-spout fluidized bed has been studied as a reference case. The experimental results obtained with PIV and PEPT agree very well for all the three cases, showing the good performance of these techniques. The DPM simulation results slightly deviate from the experiments which is attributed to particle–wall effects that are more dominant in pseudo-2D beds than in 3D systems. The investigated multiple-interacting-spouts regime is a fully new flow regime that does not appear in single-spout fluidized beds. Two flow patterns have been observed, viz. particle circulation in between the spouts near the bottom of the bed, and an apparent single-spout fluidization motion at a higher location upwards in the bed. These findings show that the presence of multiple spouts in a spout fluidized bed highly affect the flow behaviour, which cannot be distinguished by solely investigating single-spout fluidized beds.

Experimental application of particle imaging to fluid velocity analysis in building drainage systems

Previous research into the hydraulic and pneumatic conditions in the pipework associated with building drainage waste and ventilation (DWV) systems has been interpreted as suggesting that the flow regime within the vertical stack consists of an annular water flow entraining a central air core with an associated pressure drop. However, previous evidence had suggested that a significant proportion of the water was found in the air core by Pink [A study of the effect of stack length on airflow in drainage stacks. BRE Current Paper, 1973; 38/73] and Wyly and Eaton [1961. Capacity of stacks in sanitary drainage systems for buildings. U.S. Department of Commerce, National Bureau of Standards, Monograph 3]. A new model has recently been proposed by Campbell and MacLeod [Investigation of the causative factors of airflow entrainment in building drainage-waste-ventilation (DWV) systems. Building Services Engineering Research Technology 1999; 20(3): 99—104] which suggests that the airflow entrainment is due to the distribution of work between the water annulus and the droplets falling in the central air core. This article describes the investigation of the velocity profile of mixed-phase fluid flow in building DWV systems utilising the particle tracking velocimetry (PTV) flow measurement technique previously established by Campbell [The application of particle tracking velocimetry as a velocity measurement technique. Building Services Engineering Research Technology 2006; 27(4): 327—40]. PTV is a non-intrusive optical flow measurement technique that supplies an instantaneous sample of velocity throughout a two-dimensional plane in the flow field. The results of the PTV investigation support the assumption that water droplets exist in the air core and have a velocity greater than that of the water annulus. Practical application: This article describes the application of particle tracking velocimetry (PTV) to the interaction between air and water in typical building drainage waste and ventilation (DWV) systems. Results indicate an unexpected distribution of mass across the stack discharge which, together with the nature of the air/water interface, governs air movement. The technique of PTV is particularly suited to this area, and represents the first steps towards eventual refinement of mathematical models designed to simulate building DWV system behaviour.

Analytical model for Rayleigh–Brillouin line shapes in air

Atmospheric lidar techniques for the measurement of wind, temperature, and optical properties of aerosols as well as nonintrusive measurement techniques for temperature, density, and bulk velocity in gas flows rely on the exact knowledge of the spectral line shape of the scattered laser light on molecules. A mathematically complex, numerical model (Tenti S6 model) is currently the best model for describing these spectra. In this paper an easy processable, alternative analytical model for describing spontaneous Rayleigh-Brillouin spectra in air at atmospheric conditions is introduced. The deviations between the analytical and Tenti S6 models are shown to be smaller than 0.85%.

Experimental characterization of the fluid dynamics in an in- vitro system simulating the peristaltic movement of the stomach wall

The difficulty in experimentally characterizing the dynamics of gastric contents during digestion has limited the knowledge required to understand and model the kinetics of food disintegration. The goal of this work was to experimentally characterize, in a closed system, the peristaltic flow of fluids with different rheological properties. An experimental apparatus was developed to reproduce the general characteristics of gastric motility, while supporting the use of a non-intrusive flow measurement technique (Particle Image Velocimetry). The apparatus consisted of a polycarbonate chamber with one neoprene wall that was continuously deformed by vertically moving a stainless steel cylinder at a speed of 3.5mm/s. The fluid dynamics of three Newtonian fluids (water, and water solutions of 10% and 95% corn-syrup) and two shear thinning fluids (water solutions of 0.15% and 0.50% CMC) were investigated. In addition, the effect of the occlusion ratio (30, 45 and 60%) on the fluid dynamics of water within the system was analyzed. Experimental results showed that the loci of maximum velocity were present in the section corresponding to the location of the hump peak. As the viscosity of the Newtonian fluid increased, higher and more localized retropulsive velocities developed. However, these differences were not observed in the dynamics of shear thinning fluid flows. As the viscosity of the fluid increased, a more ordered flow developed, but no differences were found with respect to maximum values of shear rates or vorticity. The differences in the overall flow behaviour of the two CMC solutions were even less noticeable, but they both exhibited lower shear rates and vorticities than the Newtonian fluid. By decreasing the compression ratio of the hump, the maximum water velocity within the system decreased by 45%, while the maximum values of shear and vorticity decreased by 18% and 23%, respectively. This work showed the significant effect of the rheological properties of the flow on the fluid-dynamics within a closed system due to the peristaltic deformation of its wall. From a boarder perspective, this work demonstrated the relevance of acquiring a good characterization of the rheology of gastric contents to fully characterize the fluid- mechanical forces involved in food digestion.

Validation of CFD and Thermal Hydraulics Codes by Digital Particle Image Velocimetry

Abstract Experimental validation of thermal hydraulics and CFD codes of scaled down models and full models of Nuclear Reactor components is very important for reactor system designers and reactor safety experts for optimal design and providing best safety features of the reactor systems. Over the period of time several techniques have been developed for this purpose. Among them Digital Part icle Image Velocimetry (DPIV), a laser based optical technique, is the recent, innovative, promising and flexible enough one so that it can be adapted to a large variety flows. By this technique test time is reduced significantly. DPIV is a non-intrusive optical measurement technique, which allows capturing several thousand velocity vectors within large flow fields instantaneously. DPIV technique is being used in very wide and different applications, from micro flows over combustion to supersonic flows for both industrial needs and research. 2-D DPIV facility having non-intrusive, instantaneous flow visualization with high spatial and temporal resolution features has been developed. It is used for measurement of flow velocity vectors at many (e.g. thousands) points in a flow field simultaneously and it provides instantaneous vector fields and displays velocity vectors in rea l-t ime. DPIV combines flow visualization with accurate quantitative velocity data. 2-D Velocity vectors are obtained by analysis of displacement of tracer particles on images in a known time. The development of visualizat ion tools are powerful enough to at tack the complexity of a resulting flow field but also flexible enough so that they can be adapted to a large variety of different flow. DPIV system has Laser light source, Laser beam delivery system, High speed camera interface, DPIV image acquisition & analysis software, CCD camera, computer controlled synchronizer, seeding particles & PC. This system will enhance our capability of thermal hydraulics, neutronics and mult iphysics modelling by experimental support & actual measurement of parameters, in addition to codes we had with us. Application of DPIV is must for the flow in the separation and reattachment regions where it is directly related to drag and heat transfer coefficients and for Vortex shedding. This facility is being used for basic research of code verification, code development, design optimizations and safety analysis.

Correlation of Flowfield and Acoustic field Measurements in High-Speed Jets

The present study demonstrates the capabilities of an optical deflectometry (OD) technique to provide flow field turbulence measurements that can be successfully correlated with far-field acoustic field measurements. Results from supersonic fully expanded jets are presented and show variations in the frequency content of the coherence between the flow field and the acoustic field with OD positioning. The method is applied to jets with supersonic convection speed, producing Mach wave radiation, and show the strong directionality of the emitted noise. Similar measurements performed in shock-containing jets with microphones in the forward arc reveal enhanced coherence at the same frequency as the Broad Band Shock Associated Noise. Measurements are also made with the optical sensors scanning radially outside of the jet in an attempt to obtain a measurement of the spectra in the acoustic near field. These results show an exponential decay of the signal characteristic of the hydrodynamic region, where an evanescent pressure field dominates the total pressure fluctuation. The high level of skewness in these signals also support the concept that the crackle observed in the far-field originates in the near field. Further radially, acoustic pressure fluctuations are measured and successfully correlated to the acoustic far-field, thus demonstrating another application of this non-intrusive measurement technique in jet acoustics diagnostics.

Considerations on direct stream flow measurements using video imagery: Outlook and research needs

The paper presents measurements acquired with Large-Scale Particle Image Velocimetry (LSPIV) during normal flows and floods in the Iowa River (U.S.A). For normal flows, comparison is made with measurements obtained with Acoustic Doppler Current Profilers (ADCP) in order to test LSPIV’s performance and to address concerns potentially affecting the accuracy of the measurements. The historic flood of the Iowa River during the summer of 2008 was captured for testing LSPIV capabilities during extreme flows. Lacking alternative measurements during the flood, the LSPIV measurements are compared to the rating curve extrapolated for high flows using a one-to-one discharge–stage relationship. The comparison reveals limitations of the single-values rating curve for providing discharge estimates during high flows. Finally, the paper summarizes lessons learned during these and previous LSPIV studies with the intent to chart the research needed to enhance this promising non-intrusive field measurement technique.

Analysis of Rotor-Stator-Interaction and Blade-to-Blade Measurements in a Two Stage Axial Flow Compressor

In order to improve unsteady CFD analysis for turbomachinery applications, there is still the need for high quality experimental data for validation. The first aim of this paper is to represent a unique work in providing unsteady data for the purpose of a CFD test case. Second, a detailed analysis of rotor-stator-interaction in a multistage compressor is performed by means of accompanying frequency analysis of the blading and the tip leakage flow for different indexing positions. The transonic two stage axial flow compressor is equipped with integrally bladed rotors and vanes with hub and tip shrouds with regard to a modern high pressure jet engine compressor. For detailed flow measurements both intrusive and nonintrusive measurement techniques were used. Beside pressure probes mounted with a semiconductor and microstrain gauges applied to the blades and vanes, a three component Doppler laser-two-focus velocimeter was used. The results of the time resolved pressure traverse measurements in the axial gaps as well as the analysis of the tip leakage flow show the propagation of the wakes and the potential upstream influence, which can be clearly detected by the blade passing frequencies as well. Additionally, the results of the blade-to-blade measurements impart an idea of the intrarotor-transport of the fluid and the flow phenomena within the rotor. Beside the detailed flow analysis, the preferential aim of this paper is to establish a method for the detection of flow phenomena due to the blade-row-interaction by means of a frequency analysis. This paper shows that a correlation of the fast Fourier transform results of strain gauges and semiconductor probes in the axial gaps and tip leakage flow region is a very promising starting point, especially for the analysis of forced response operating points.

An experimental study of the effect of collision properties on spout fluidized bed dynamics

In this paper we experimentally study the effect of collision properties of different particle systems on the bed dynamics of a spout fluidized bed. This is done for different flow regimes: the spout-fluidization regime (case A), the jet-in-fluidized-bed regime (case B) and the spouting-with-aeration regime (case C). The considered particle systems comprise glass beads, γ-alumina oxide and zeolite 4A particles, which are all classified as Geldart D. A non-intrusive measurement technique is used, viz. particle image velocimetry (PIV) to measure the particle flow field in a pseudo two-dimensional (2D) spout fluidized bed. Additionally, digital images are analyzed using a newly developed digital image analysis (DIA) algorithm to evaluate the particle volume fraction. It is demonstrated that the new proposed DIA algorithm provides reliable information on the particle volume fraction distribution, showing that it is a powerful tool when combined with PIV. The added value of DIA is confirmed by comparing the particle velocity fields and volumetric particle fluxes. The effect of the collision properties for glass beads, γ-alumina oxide and zeolite 4A particles has been studied in three flow regimes, i.e. the intermediate/spout-fluidization regime (case A), the jet-in-fluidized-bed regime (case B) and the spouting-with-aeration regime (case C). For each flow regime, the particle volume fraction shows small differences between the different particle systems. For the γ-alumina oxide and zeolite 4A particles, the spout channel is less stable for the cases A and C. The particle fluxes display also small differences between the particle systems for each flow regime.

Convective heat transfer studies in macro and mini channels using digital interferometry

Convective heat transfer in micro and mini channels has been recommended as an effective heat removal method for various electronic packages and systems. As the traditional method of temperature measurement in channels using the thermocouple probe disturbs the flow field leading to measurement errors, a non-intrusive measurement technique, such as an optical method is preferable for temperature and heat transfer measurement in mini channels. In the present work, convective heat transfer studies have been performed on water flowing through channels of small cross sections of hydraulic diameter 4 mm and 3 mm, using digital interferometric technique. The channels are fabricated using high quality optical glass and aluminum blocks. Mach–Zehnder Interferometry is used for obtaining the temperature distribution in the channels. The interferograms grabbed using a CCD camera, coupled to a computer and digital image processing technique, has been used for obtaining the temperature distribution from the fringes. The temperature profiles are obtained at different sections of the channels for various values of the average Reynolds number and various heating levels. The local and average heat flux values are obtained from the constructed temperature distributions. Results of parametric studies are compared and contrasted with relevant entry length solutions from the literature.

Simultaneous Measurement of Three-Dimensional Soot Temperature and Volume Fraction Fields in Axisymmetric or Asymmetric Small Unconfined Flames With CCD Cameras

Abstract A nonintrusive measurement technique is presented numerically for simultaneous measurement of three-dimensional (3D) soot temperature and volume fraction fields in the axisymmetric or asymmetric flames with charge-coupled device (CCD) cameras. CCD cameras were introduced to capture the flame images for obtaining the line-of-sight radiation intensities. The distributions of local emission source under two wavelengths can be deduced through solving the reconstruction matrix equation by the least-square QR decomposition method from the knowledge of the line-of-sight radiation intensities of the flames. The two-color distributions of the local emission source were used to retrieve the soot temperature and volume fraction distributions. The effects of the discrete ray number of CCD cameras, the number of CCD cameras, and the system signal-to-noise ratio (SNR) on the measurement were investigated. The results show that for accurate measurement of soot volume fraction field, the CCD cameras number should not be less than four and the system SNR can be as low as 54 dB. The proposed technique can be capable for reconstructing the 3D soot temperature and volume fraction fields in both axisymmetric and asymmetric flames well.

EXPERIMENTAL INVESTIGATION OF THE PHENOMENON OF OIL BREAKUP IN AN ENGINE CRANKCASE

A phenomenological study of the characteristics of a two-phase, oil and air mixture was undertaken in a combustion engine crankcase model at speeds of up to 6000 rpm. The idealized model comprised production components and tolerances. Nonintrusive measurement techniques, such as PIV and PDA and high-speed photography, were applied to the study of the oil aerosol and liquid films. Agitated oil pools and impingement on the crankcase surfaces contributed to the aeration of oil in the sump due to windage effects. A mean, wakelike, flow pattern was observed that lagged the crankshaft rotation. Harmonic frequencies were recorded that could be identified with the passage of the position of the maximum crank profile radii and a delay time related to the involute-shaped cord and droplet trajectories induced by drag forces. Highly unsteady flow conditions were measured close to the chamber walls. Three classical breakup modes were identified over three speed ranges. Sheet, ligament, and droplet breakup were observed in the ranges of idle to 1800, 4200, and 6000 rpm. Classification of the particle size distribution for the break-up modes was carried out using the PDA technique. Droplet diameter and velocity data varied in the ranges of 2 μm (dmin) to 130 μm (dmax) and 0−40 ms−1 at 6000 rpm. The ratio of the droplet diameter, dmin;max to a characteristic diameter D at which the oil was observed to break away was compared to the disk Bond number, BoD. For the largest measured droplets, the ratio was approximated by dmax/D = 1.30BoD−0.33 . The disk Bond number was 2.21, while the empirical constant was in the range of 1.82−2.39. The result showed that an appropriate correction must be applied to the universal power law, proposed by Simpkins in 1997 for the estimate of the primary droplet size generated by a spinning disk homogenous atomizer, which had overpredicted the droplet sizes in the case of the crankshaft.

PIV measurements of turbulent jet and pool mixing produced by a steam jet discharge in a subcooled water pool

This experimental research is on the fluid-dynamic features produced by a steam injection into a subcooled water pool. The relevant phenomena could often be encountered in water cooled nuclear power plants. Two major topics, a turbulent jet and the internal circulation produced by a steam injection, were investigated separately using a particle image velocimetry (PIV) as a non-intrusive optical measurement technique. Physical domains of both experiments have a two-dimensional axi-symmetric geometry of which the boundary and initial conditions can be readily and well defined. The turbulent jet experiments with the upward discharging configuration provide the parametric values for quantitatively describing a turbulent jet such as the self-similar velocity profile, central velocity decay, spreading rate, etc. And in the internal circulation experiments with the downward discharging configuration, typical flow patterns in a whole pool region are measured in detail, which reveals both the local and macroscopic characteristics of the mixing behavior in a pool. This quantitative data on the condensing jet-induced mixing behavior in a pool could be utilized as benchmarking for a CFD simulation of relevant phenomena.

Calibrations and the measurement uncertainty of wide-band liquid crystal thermography

Wide-band liquid crystal thermography is a high-resolution, non-intrusive optical technique for full-field temperature measurement. The paper presents comprehensive experimental results on the calibration and the measurement uncertainty for a thermochromic liquid crystal (TLC) with a bandwidth of 20 °C, examining the effects of the use of an image noise reduction technique, the lighting angle, the TLC coating thickness and the coating quality on the hue–temperature curve and the measurement uncertainty. It is found that combined with the image noise reduction technique of a 5 × 5 median filter, the measurement accuracy of the TLC can be significantly improved, and the high-accuracy usable bandwidth of the TLC can be considerably enlarged. The lighting angle has distinctive effects on the hue curve and the measurement uncertainty of the TLC, and a smaller lighting angle provides a smaller measurement uncertainty. The coating thickness has an appreciable effect on the TLC hue–temperature curve, but has a non-distinctive effect on the measurement uncertainty providing the coating thickness is over 20 µm. It is also found that the TLC coating quality has distinctive effects on the TLC hue curve and the measurement uncertainty. A finely prepared TLC coating produces a wider range of hue over the active temperature range, a considerably smaller measurement uncertainty and a larger high-accuracy usable bandwidth than the roughly prepared coating.

A High-speed Nature Laminar Flow Airfoil and Its Experimental Study in Wind Tunnel with Nonintrusive Measurement Technique

This article deals with an experimental study on the aerodynamic characteristics of a low-drag high-speed nature laminar flow (NLF) airfoil for business airplanes in the TST27 wind tunnel at Delft University of Technology, the Netherlands. In this experiment, in an attempt to reduce the errors of measurement and improve its accuracy in high-speed flight, some nonintrusive measurement techniques, such as the quantitative infrared thermography (IRT), the digital particle imaging velocimetry (PIV), and the shadowgraphy, are applied to obtain precise data about transition locations, separation on trailing edges, and lift/drag characteristics. The experimental results reveal that, in the high-speed flight, small angles of attack are helpful in retaining long laminar flows, preventing the vortex at the trailing edge from moving forward and thus imparting the airfoil and the high-lift and low-drag characteristics. The comparison of the measured results to the calculated ones proves the acceptability of the airfoil and its aerodynamic characteristics satisfying the design requirements.