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Instrumentation in Aerospace Simulation Facilities, 2001. 19th International Congress on ICIASF 2001

Date 27-30 Aug. 2001

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Displaying Results 1 - 25 of 53
  • ICIASF 2001 Record, 19th International Congress on Instrumentation in Aerospace Simulation Facilities (Cat. No.01CH37215)

    Publication Year: 2001
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    Freely Available from IEEE
  • Author biographies

    Publication Year: 2001 , Page(s): 457 - 478
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    Freely Available from IEEE
  • Recent topics in fast-responding pressure-sensitive paint technology at National Aerospace Laboratory

    Publication Year: 2001 , Page(s): 25 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB) |  | HTML iconHTML  

    This paper reviews the recent advances in fast-responding Pressure-Sensitive Paint (PSP) technology at National Aerospace Laboratory in Japan. Since NAL started a research program on PSP in 1994, much effort has been focused on the development of PSP for unsteady pressure measurements. In recent study, we have made a substantial progress in the fast PSP formulations. This includes the development of a PSP using a high polymer called poly(TMSP) and chemisorptive PSPs based on anodized-aluminum. To investigate the response characteristics of these paints, we have made systematic tests using a pressure chamber with a fast-acting solenoid-type valve and a shock tube. A summary of these experimental investigations is given in this paper with an emphasis on the relationship between the response time and the physical properties of binder materials. In addition, the feasibility tests conducted in a short-duration hypersonic shock tunnel and a shock tube are present View full abstract»

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  • Laser light scattering diagnostic for measurement of flow velocity in vicinity of propagating shock waves

    Publication Year: 2001 , Page(s): 48 - 58
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB) |  | HTML iconHTML  

    A laser light scattering diagnostic for measurement of dynamic flow velocity at a point is described. The instrument is being developed for use in the study of propagating shock waves and detonation waves in pulse detonation engines under development at the NASA Glenn Research Center (GRC). The approach uses a Fabry-Perot interferometer to measure the Doppler shift of laser light scattered from small (submicron) particles in the flow. The high-speed detection system required to resolve the transient response as a shock wave crosses the probe volume uses fast response photodetectors and a PC based data acquisition system. Preliminary results of measurements made in the GRC Mach 4, 10×25 cm supersonic wind tunnel are presented. Spontaneous condensation of water vapor in the flow is used as seed. The tunnel is supplied with continuous air flow at up to 45 psia; the flow is exhausted into the GRC laboratory-wide altitude exhaust system at pressures down to 0.3 psia View full abstract»

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  • The development and operational aspects of a signal transfer system for use in wind tunnel propeller models

    Publication Year: 2001 , Page(s): 353 - 359
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    This paper describes a Signal Transfer System (STS) for use in a wind tunnel model propeller. In order to extend the capacity of a conventional mechanical slip ring assembly an electronic multiplexer has been developed, which is located in the rotating part of a propeller-hub. The amplified transducer signals are multiplexed, digitised and transferred over the slip ring assembly located in the propeller shaft. A demultiplexer unit processes the signals in order to make them available, in analogue format, for a wind tunnel data acquisition system. NLR has developed the STS for use in a specific Wind Tunnel model propeller. Due to space limitations in the model a slip ring assembly had to be applied, which had an insufficient number of slip rings to transfer all signals directly. Two STS have been successfully operated with two model propellers, throughout a number of tests in several European wind tunnels. Special attention has been paid to the operational aspects of the system. A brief overview is presented for a future development resulting in a fully contact-less transfer system, replacing mechanical slip ring assemblies View full abstract»

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  • High temperature surface measurements using lifetime imaging of thermographic phosphors: bonding tests

    Publication Year: 2001 , Page(s): 171 - 176
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    Temperature-sensitive paint (TSP) comprised of thermally sensitive phosphor can provide a viable means for noncontact thermometry in wind tunnel and other aeropropulsion applications. Described here are recent results aimed at developing a phosphor and binder system that will cover a wide temperature range, ambient to 1000°C. The phosphor/binder mixture is to be sprayed directly on the surface with an airbrush. Whereas many surfaces are candidates for various uses, the present effort concerned silicon carbide, silicon nitride and silica substrates. Initial tests show that a phosphor mixture with two water-soluble materials, designated LK and HPC and manufactured by ZYP Inc., adhered well to these substrates. This same material was earlier shown to function well on a high strength nickel alloy View full abstract»

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  • Unsteady flow phenomena in an axisymmetric combustor

    Publication Year: 2001 , Page(s): 59 - 69
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB) |  | HTML iconHTML  

    The unsteady flow characteristics prevailing in a simple axisymmetric combustor are described. Unexpected bimodal velocity distributions are present in various regions of the flow, which are not accounted for in mathematical models. Understanding and accurate modeling of such flow behavior is essential as it can significantly affect the fuel/air mixing process, thus impacting combustion efficiency and emissions View full abstract»

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  • Measurements of dynamic stability derivatives using direct forced oscillation technique

    Publication Year: 2001 , Page(s): 275 - 282
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (560 KB) |  | HTML iconHTML  

    The subject of the experimental investigation presented in this paper is to measure the dynamic stability derivatives of a generic combat aircraft model in the Ankara Wind Tunnel by using the direct forced oscillation technique. The model, used for the tests is the AGARD, Standard Dynamic Model (SDM). The aerodynamic loads acting on the model are measured with a five component internal strain gauge balance placed inside the oscillating model. The paper presents the experimental set-up used to create the oscillatory motion in pitch for the model and the related motion control and the data acquisition units to measure the dynamic loads, and discussed the results of the measurements View full abstract»

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  • Measurement of separating flow structures using a multiple-camera DPIV system

    Publication Year: 2001 , Page(s): 82 - 93
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1120 KB) |  | HTML iconHTML  

    A novel multiple-camera system for the recording of digital particle image velocimetry (DPIV) images acquired in a two-dimensional separating/reattaching flow is described. The measurements were performed in the NASA Langley Subsonic Basic Research Tunnel as part of an overall series of experiments involving the simultaneous acquisition of dynamic surface pressures and off-body velocities. The DPIV system utilized two frequency-doubled Nd:YAG lasers to generate two coplanar, orthogonally-polarized light sheets directed upstream along the horizontal centerline of the test model. A recording system containing two pairs of matched high resolution, 8-bit cameras was used to separate and capture images of illuminated tracer particles embedded in the flow field. Background image subtraction was used to reduce undesirable flare light emanating from the surface of the model, and custom pixel alignment algorithms were employed to provide accurate registration among the various cameras. Spatial cross correlation analysis with median filter validation was used to determine the instantaneous velocity structure in the separating/reattaching flow region illuminated by the laser light sheets. In operation the DPIV system exhibited a good ability to resolve largescale separated flow structures with acceptable accuracy over the extended field of view of the cameras. The recording system design provided., enhanced performance versus traditional DPIV systems by allowing a variety of standard and non-standard cameras to be easily incorporated into the system View full abstract»

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  • Development of a quantitative flow visualization tool for applications in industrial wind tunnels

    Publication Year: 2001 , Page(s): 125 - 134
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1744 KB) |  | HTML iconHTML  

    The development of a measurement system to visualize, classify (based on topological features) and quantify complex flows in large scale wind tunnel experiments is described. A new approach is sought where the topological features of the flow, e.g. stream lines, separation and reattachment regions, stagnation points and vortex lines are extracted directly and preferably visualized in realtime in a virtual wind tunnel environment. The system is based on a three dimensional particle tracking method (3D-PTV) using a stereo arrangement of 2 CCD cameras. A frame rate of 120 frames/s allows measurements at high flow velocities. For the 3D-PTV method an approach is taken where the tracer particles are recorded such that consecutive frames form continuous path lines. The 3-dimensional positions and shapes of the particle path lines are reconstructed by means of the epipolar constraint and the stereo camera model. The particle path segments which contain both velocity and topological information are then analysed to extract the relevant information. Neutrally buoyant helium bubbles are used as tracer particles. Matching the density of the ambient air, the bubbles are ideal flow tracers in this respect View full abstract»

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  • Doppler Global Velocimetry (DGV) data in circular jets

    Publication Year: 2001 , Page(s): 219 - 230
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB) |  | HTML iconHTML  

    A two-component Doppler Global Velocimeter (DGV) system has been improved through the use of vapor-limited iodine cells that have temperature-independent responses, along with non-polarizing beam splitters and lower f-number lenses. Two-component DGV velocity measurements have been obtained for a 1 inch diameter uniform circular jet flow at a nominal exit velocity of 60 m/sec, as well as for an annular jet and a swirling jet. These data generally agree with earlier point Doppler velocimeter (pDv) and hot wire anemometer results to within about 2-4 m/sec, and display a total variability from a smooth curve of ± 2-3 m/sec. Exceptions to this level of accuracy are noted in regions of significant secondary scattering, due to scattered laser light that is reflected off of the lip of the jet nozzle, as well as in regions of low smoke seeding levels, resulting in a low signal-to-noise ratios. A significant amount of the variability of the data from a smooth curve is due to the flat field correction View full abstract»

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  • Seedless laser velocimetry using heterodyne laser-induced thermal acoustics

    Publication Year: 2001 , Page(s): 309 - 319
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB) |  | HTML iconHTML  

    A need exists for a seedless equivalent of laser Doppler velocimetry (LDV) for use in low-turbulence or supersonic flows or elsewhere where seeding is undesirable or impractical. A compact laser velocimeter using heterodyne non-resonant laser-induced thermal acoustics (LITA) to measure a single component of velocity is described. Neither molecular (e.g. NO2) nor particulate seed is added to the flow. In non-resonant LITA two beams split from a short-pulse pump laser are crossed; interference produces two counterpropagating sound waves by electrostriction. A CW probe laser incident on the sound waves at the proper angle is diffracted towards a detector. Measurement of the beating between the Doppler-shifted light and a highly attenuated portion of the: probe beam allows determination of one component of flow velocity, speed of sound, and temperature. The sound waves essentially take the place of the particulate seed used in LDV. The velocimeter was used to study the flow behind a rearward-facing step in NASA Langley Research Center's Basic Aerodynamics Research Tunnel. Comparison is made with pitot-static probe data in the freestream over the range 0 m/s - 55 m/s. Comparison with LDV is made in the recirculation region behind the step and in a well-developed boundary layer in front of the step. Good agreement is found in all cases View full abstract»

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  • Processing time series data (velocity, shear stress) from the pulse width modulated-constant temperature anemometer (PWM-CTA)

    Publication Year: 2001 , Page(s): 448 - 456
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB) |  | HTML iconHTML  

    The digital output from the PWM-CTA represents the short duration (e.g., 20μsec) true time average of the analog velocity or shear stress. The developed techniques to extract the moments of the velocity (or shear stress) distribution and to create a regular time series are presented View full abstract»

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  • High spatial resolution MEMS surface pressure sensor array for transonic compressor IGV measurement

    Publication Year: 2001 , Page(s): 231 - 239
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB) |  | HTML iconHTML  

    A high spatial resolution MEMS pressure sensor array consisting of 60 transducers for the measurement of unsteady surface pressures on the inlet guide vane (IGV) of a transonic compressor rig is presented. Measurements from this sensor array will be used to investigate three-dimensional unsteady vane/blade interaction aeromechanical forcing functions in a modern, highly loaded compressor stage. Included are details of the design and construction of the MEMS array and electronic interrogation circuitry used for acquisition of the 60 transducer signals using the available data acquisition system. In addition, the MEMS pressure sensor array is used to acquire experimental data. A sample of the data is reduced and shown to give excellent agreement both in the time and frequency domain when compared with previous instrumentation using traditional individual sensor mounting methods. Finally, a significant cost saving of 44% in instrumenting the IGV is realized over traditional instrumentation methods along with substantial benefits in the handling of the sensor wiring View full abstract»

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  • Pressure probe designs for dynamic pressure measurements in a supersonic flow field

    Publication Year: 2001 , Page(s): 417 - 426
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1032 KB) |  | HTML iconHTML  

    A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a 10- by 10-foot supersonic wind tunnel test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor stall and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed View full abstract»

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  • Two-axis Scheimpflug focusing for particle image velocimetry

    Publication Year: 2001 , Page(s): 114 - 124
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1520 KB) |  | HTML iconHTML  

    The objective of this work is to demonstrate the capabilities of a two-axis, three-dimensional Particle Image Velocimetry (PIV) system for use as a largescale wind tunnel research tool. A two-axis PIV system provides the capability for camera placement virtually anywhere within a three-dimensional space relative to the laser sheet plane of measurement. The Scheimpflug focusing method is applied in two orthogonal axes to achieve off-axis focusing. The two-axis, three-dimensional PIV system uses off-axis stereoscopic viewing to determine two perspective measurements of a three-dimensional velocity field within the laser sheet. A unique calibration procedure is used to determine the optical parameters that describe the position of the camera systems and which are necessary to perform the three-dimensional reconstruction of the displacements. This paper presents this unique calibration for a two-axis, three-dimensional PIV system. This two-axis, three-dimensional PIV system was demonstrated first by measuring three-dimensional displacements of a target. Maximum instantaneous errors are estimated as 2% or less for all velocity components based upon the measured target displacements, and these error estimates were verified by a propagation of errors calculation. The error estimates are for instantaneous displacements and include all error sources. The two-axis, three-dimensional PIV system was also used to make measurements of the freestream velocity within a wind tunnel. The out-of-plane freestream component of velocity measured by the PIV system differed from the expected value by less than 1.1 % View full abstract»

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  • Experimental investigation of transverse jet interaction on a missile body using laser velocimetry and flow visualization

    Publication Year: 2001 , Page(s): 295 - 301
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    An experimental investigation of the interaction between a lateral jet issuing from a missile body and the oncoming external flow is presented. The experiments were carried out in the ISL supersonic blow-down wind tunnel at a Mach number of 3. The test model was a cone-cylinder-flare body with a side jet nozzle located on the cylindrical section, representing a simple generic high-speed missile configuration. For this study, three distinct flow conditions were chosen which are characterized by a jet ejection pressure ratio of 50, 70 and 97, respectively. Flow velocity measurements were performed with the aid of a two-component laser Doppler velocimeter (LDV). In addition, flow visualization techniques were used in order to confirm the LDV results. Combined with previous surface pressure measurements, the present investigation yields a consistent picture of the jet-induced flow field comprising a separation zone and various shock waves upstream from the jet exit. This detailed knowledge of the flow structure is required for evaluating the performance of lateral jet control systems View full abstract»

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  • Thin film sensors for surface measurements [in aerospace simulation facilities]

    Publication Year: 2001 , Page(s): 196 - 203
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB) |  | HTML iconHTML  

    Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100°C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge is provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date are described. Finally, the results are provided of the current effort to demonstrate the capabilities of the multifunctional gauge View full abstract»

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  • Dynamic pressure measurements using silicon carbide transducers

    Publication Year: 2001 , Page(s): 240 - 245
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    Pressure sensors capable of operating at higher temperatures have long been sought for testing of aircraft engines, since each improvement in sensor durability opens new areas of the engine to the straightforward measurement of rapidly varying pressures. A silicon carbide pressure sensor has been developed which can operate at 500°C, a temperature at which the mechanical properties of silicon, the most commonly used pressure sensor material, are severely degraded. The prototype SiC pressure transducer was successfully tested on a gas turbine engine, thereby demonstrating its ability to survive the hostile engine environment. Testing in a shock tube showed the packaged sensor to have a natural frequency of 30 kHz, which is adequate for many dynamic pressure measurement applications. It is expected that the frequency response could be increased by a simple modification of the package to reduce the setback of the SiC die View full abstract»

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  • Time varying parameter estimation with decomposition system

    Publication Year: 2001 , Page(s): 360 - 368
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    This paper presents an algorithm for on line parameter estimation with decomposition of MIMO linearized time varying system. The test data is the process and measurement noise. Generally speaking, the former online parameter estimation method for MIMO system needed either normalizing the system math model or a lot of calculation for inverse matrix in estimating processing. It is not only takes much operational time, but also easily diverges when the matrix is irreversible. The method that we present here hierarchically estimates parameters so that can avoid the inverse matrix and follow the time varying parameter step by step. That could raise the calculation precision and ensure the proceeding convergence. Using the simulation flight test data in processing and measurement noise, the method has been examined View full abstract»

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  • Accuracy limitations of lifetime-based pressure-sensitive paint (PSP) measurements

    Publication Year: 2001 , Page(s): 5 - 16
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1088 KB) |  | HTML iconHTML  

    PSP systems determine air pressure by measuring the luminescence lifetime of an oxygen-quenched luminophor in a porous matrix. While traditionally lifetime was inferred from measurements at different pressures, it is becoming increasingly common to make direct lifetime measurements by taking images at different points on the luminescence decay curve using a gated camera. Here, the accuracy of the lifetime method is evaluated through theoretical analysis, bench top studies, and small scale wind tunnel tests, with the primary aim of determining whether the lifetime method is suitable for measurements in very low speed flows (Mach~0.1). It is found that the luminescence lifetime of a PSP-coated surface can vary from point to point even at constant pressure and temperature. This variation is a significant source of error in low speed measurements, and can be reduced significantly by careful paint application procedures View full abstract»

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  • PIV investigation on airfoil with ice accretions and resulting performance degradation

    Publication Year: 2001 , Page(s): 94 - 105
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1424 KB) |  | HTML iconHTML  

    An experimental study was conducted to investigate the effect of ice accretions on the aerodynamic characteristics of a 100 mm-chord NACA 0012 airfoil section. Four different configurations of the airfoil model were considered: clean profile and profile with glaze, rime and mixed ice-accretion. shapes. The considered shapes were derived from measurements performed at the NASA Lewis Icing Research Tunnel (IRT). Tests were performed in the closed test section of an open circuit calibration tunnel: the chord Reynolds number was about 200000. Velocity field was measured by means of PIV technique on the clean and mixed airfoils, whereas aerodynamic coefficients for all the different ice accretion shapes were measured as a function of airfoil incidence, by means of a three component balance. The experimental results show remarkable aerodynamic characteristics decay due to the simulated ice formation: glaze configuration shows worst performances with inversion of the lift-incidence curve and a dramatic increase of the drag coefficient. PIV measurements show large regions of separated flow even at low incidence and for moderate amount of ice (mixed shape): in fact, due to the low chord Reynolds number, no flow reattachment occurs downstream the separation View full abstract»

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  • Supersonic flow measurement and computation of a lobed-mixer for trapped vortex combustors

    Publication Year: 2001 , Page(s): 427 - 437
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB) |  | HTML iconHTML  

    This paper described an experimental and computational effort aimed at understanding diffuser exit profiles, for a lobed duct design that will potentially be used for higher Mach combustion evaluations in the Trapped Vortex Combustor (TVC). Experimental hardware was described, using CAD solid models to show the major flow features present in this diffuser/combustor system. Initial CFD simulations were compared with experimental data, showing good agreement with total pressure measurements, but unacceptable agreement with static pressure measurements, all taken with a Pitot-static tube. Even taking axial and radial variations in positioning of either the probe or the CFD sampling plane, checking the pressure transducer calibrations, and verification of the CFD boundary conditions, poor agreement remained. The CFD modeling methodology was modified to take into account the presence of the Pitot-static probe, and the simulations were re-run. Flow field contours of static pressure and Mach number, in the vicinity of the probe, verified that the probe caused large, local disturbances. The graphics also showed that large axial, radial and tangential velocity and pressure gradients near the static pressure ports were acting on the probe, and were reflected in the experimental data points. With the probe included in the CFD model, six new simulations were run, with the probe traversed through the model as in the experiment. These results were very encouraging, in that the established good agreement between measured and predicted values for total pressure were repeated under the new methodology, and that static pressure profiles were now in good agreement View full abstract»

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  • 360° PSP measurements in transonic flow

    Publication Year: 2001 , Page(s): 149 - 158
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB) |  | HTML iconHTML  

    Integrated surface pressure distribution measurements using the PSP technique on a three-dimensional aircraft model with a number of various flaps, rudders and ailerons were performed at angles of attack between -4° to 36°, angles of sideslip between -13° to 13° for Mach numbers from 0.6 to 0.95. In such cases, if the pressure distribution around the model is determined, forces and moments can be calculated. In addition comparisons with conventional balance techniques are possible. The main challenge to get good PSP results on one hand is the arrangement of hardware, components of model illumination and camera observation - especially in the handling of eight simultaneously operating CCD cameras. On the other hand the software should be able to handle in a short time all the necessary synchronization between the PSP-system and wind tunnel, all PSP images, correction of lens errors, model deformation etc.. This paper describes how these problems are solved. A large number of results were mainly obtained on the AerMacchi M346 trainer aircraft model in May 2000 in the DNW-HST at Amsterdam View full abstract»

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  • An optical position monitoring system for investigation of model displacement and transient motion of wind tunnel models

    Publication Year: 2001 , Page(s): 140 - 143
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    A nonintrusive optical model displacement monitoring system is presented, which was primarily developed for wind tunnel model monitoring purposes. To solve the described problem an optical system has been developed which basically focuses the model, or part of it, onto an image plane where a line sensor is placed, utilising four independent line CCD sensors with a data rate of 6.4 kHz. To evaluate the data from the line sensors digital image processing is used to transform the data from the sensor frame of reference to the wind tunnel co-ordinate system leading to the actual model position within the wind tunnel frame of reference. The spatial resolution of the system is better than 0.3 %. The position monitoring system has been successfully applied in the DNW-TWG. The position of a delta wing model has been determined by means of the newly developed optical position monitoring system of DLR. It was possible to determine the displacement due to mean loads and the transient motion of the model for different Mach numbers, different rolling rates and angles of attack up to 25° View full abstract»

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