An account is given of the features and performance of a new LDA technique suitable for unsteady ... more An account is given of the features and performance of a new LDA technique suitable for unsteady boundary-layer measurements around an oscillating model. The apparatus employs a fiber-optic optical probe that is embedded within the moving model, thereby yielding a direct velocity measurement in a reference frame that is linked to the moving wall. Instantaneous velocity profiles and boundary layer characteristics are thereby obtained in a reference frame in relative motion. Attention is given to illustrative performance results of the method for unsteady flow transition and separation.
Comparisons are made of the transverse coherence length (r0) and isoplanatic angle theta(0) deriv... more Comparisons are made of the transverse coherence length (r0) and isoplanatic angle theta(0) derived from measurements taken with the Flatlands very high frequency (VHF) radar, an r0 system, an isoplanometer, and temperature fluctuation sensors mounted on a thermosonde. The site was selected because of the lack of orographic effects on airflow and the refractive index structure parameter (Cn2). The radar
The present paper describes an experiment in which laser velocimetric methods are employed to inv... more The present paper describes an experiment in which laser velocimetric methods are employed to investigate the drag mechanisms of a helicopter rotor in hover. Emphasis is on the development of a measurement technique capable of quantifying, the contribution of rotor profile drag to total power required. The scheme devised employs a 2-D LV system to measure the axial and tangential velocity field in the vicinity of the rotor blade. Application of a combined Kutta and Momentum Equation (KME) along a closed contour surrounding the blade section provides a measure of the local sectional normal and shear forces. A detailed survey of the rotor blade's near wake region is then performed in an attempt to directly determine the streamwise, velocity deficit. Integration of the resulting velocity profiles provides a measure of the profile drag. Accuracy of the method is checked by performing measurements at conditions of very low lift and by introducing blade surface modifications which agg...
This report focuses on the boundary layer (BL) velocity distribution in the inboard region of a t... more This report focuses on the boundary layer (BL) velocity distribution in the inboard region of a tiltrotor blade. The instrumentation consists of a Laser Doppler Velocimeter embedded in the inboard region of the blade. This set up allows measuring the chordwise and spanwise component of the boundary layer velocity from a distance of 0.3 mm to 20 mm along a direction normal to the blade surface. The experiments were carried out on a two-bladed rotor with a blade geometry close to the one of CAMRAD II model of TRAM. The blade section located at r/R=0.3 was explored in three abscissa x/C=0.10; 0.33; 0.54, and for 3 pitch angles, two of them at values lower than the static stall angle of incidence, the third at a higher value. During the tests the tip Mach number was maintained constant at M(sub tip)=0.22. Results obtained on the velocity components have allowed characterizing the different aspects of the BL. At low incidences, chordwise velocity profiles exhibit a turbulent behavior (po...
_______________________________________________________________________________________ Abstract ... more _______________________________________________________________________________________ Abstract The paper focuses on stereoscopic PIV-3C measurements performed to investigate the vortical flow generated in the wake of helmets dedicated to Time Trial (TT) stages. The objective is to characterize the wake flow of TT helmet shapes and to provide the characteristics of the wake generated by different streamlined helmet geometries. The study specifically aims to provide detailed flow databases on helmet wakes in order to improve our understanding to identify efficient factors that may provide an efficient drag force reduction. Experiments are carried out in the ISM wind tunnel at a freestream velocity close to 14 ms -1 . The use of a laser light technique does not allow testing on human and PIV measurements are thus performed on a rigid articulated mannequin (full scale 1/1) installed on the bicycle. The ensemble mannequin-bicycle is mounted on a force measurement platform in the wind t...
The present work is focused on the aerodynamic study of different parameters, including both the ... more The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist's upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results...
Water science and technology : a journal of the International Association on Water Pollution Research, 2002
The Mid North Rivers Management Planning Project (MNRMPP) of the Environment Protection Agency, D... more The Mid North Rivers Management Planning Project (MNRMPP) of the Environment Protection Agency, Department for Environment and Heritage began as a response to community concerns regarding watercourse related issues in the Mid North of South Australia. In response to these concerns the MNRMPP project team developed rapid, cost effective methods to collect and assess data, establish collaborative partnerships with stakeholder organisations, ensure community involvement, and initiate mechanisms to sustain local involvement past the life of the project. Environmental water requirements were identified, along with key watercourse management issues; the integration of these two components of the study enabled more informed decision making regarding watercourse management within the study area. The integration of these components and the involvement of the community and stakeholders through all components of the project has resulted in a sense of ownership and an increase in awareness of w...
Topics: Bicycle. Abstract: During a time-trial (TT) stage on flat track at 50 Km.h-1, aerodynamic... more Topics: Bicycle. Abstract: During a time-trial (TT) stage on flat track at 50 Km.h-1, aerodynamic drag force represents 90% of the power developed by the runner (Belluye and Cid, 2001). Given the drag resistance impact on TT performances, aerodynamics optimization of posture ...
Abs tract This paper concerns a collaborative research work between DLR of Göttingen and LABM of ... more Abs tract This paper concerns a collaborative research work between DLR of Göttingen and LABM of Marseille which aims to create a new experimental data base characterizing the tilt-rotor wake and the associated vortex structures. This study will provide detai led flow data on the aerodynamic interactions causes which occur on a tilt-rotor aircraft including a rotor, a nacelle, a fixed wing and an e nd plate simulating the fuselage. Experiments have been performed in the LABM S1L wind-tunnel at 3 different flight configurations which correspond to hover, conversion and cruise flights. The stereoscopic PIV system generates an illuminating laser sheet in a Z-plane normal to the uniform free stream velocity U8. PIV measurements have been performed at different Z-planes distributed at different distance downstream the rotor (in the wake region between the rotor and the wing and above the fixed wing) in both the conversion and cruise flight configurations and for different parametric cond...
An account is given of the features and performance of a new LDA technique suitable for unsteady ... more An account is given of the features and performance of a new LDA technique suitable for unsteady boundary-layer measurements around an oscillating model. The apparatus employs a fiber-optic optical probe that is embedded within the moving model, thereby yielding a direct velocity measurement in a reference frame that is linked to the moving wall. Instantaneous velocity profiles and boundary layer characteristics are thereby obtained in a reference frame in relative motion. Attention is given to illustrative performance results of the method for unsteady flow transition and separation.
Comparisons are made of the transverse coherence length (r0) and isoplanatic angle theta(0) deriv... more Comparisons are made of the transverse coherence length (r0) and isoplanatic angle theta(0) derived from measurements taken with the Flatlands very high frequency (VHF) radar, an r0 system, an isoplanometer, and temperature fluctuation sensors mounted on a thermosonde. The site was selected because of the lack of orographic effects on airflow and the refractive index structure parameter (Cn2). The radar
The present paper describes an experiment in which laser velocimetric methods are employed to inv... more The present paper describes an experiment in which laser velocimetric methods are employed to investigate the drag mechanisms of a helicopter rotor in hover. Emphasis is on the development of a measurement technique capable of quantifying, the contribution of rotor profile drag to total power required. The scheme devised employs a 2-D LV system to measure the axial and tangential velocity field in the vicinity of the rotor blade. Application of a combined Kutta and Momentum Equation (KME) along a closed contour surrounding the blade section provides a measure of the local sectional normal and shear forces. A detailed survey of the rotor blade's near wake region is then performed in an attempt to directly determine the streamwise, velocity deficit. Integration of the resulting velocity profiles provides a measure of the profile drag. Accuracy of the method is checked by performing measurements at conditions of very low lift and by introducing blade surface modifications which agg...
This report focuses on the boundary layer (BL) velocity distribution in the inboard region of a t... more This report focuses on the boundary layer (BL) velocity distribution in the inboard region of a tiltrotor blade. The instrumentation consists of a Laser Doppler Velocimeter embedded in the inboard region of the blade. This set up allows measuring the chordwise and spanwise component of the boundary layer velocity from a distance of 0.3 mm to 20 mm along a direction normal to the blade surface. The experiments were carried out on a two-bladed rotor with a blade geometry close to the one of CAMRAD II model of TRAM. The blade section located at r/R=0.3 was explored in three abscissa x/C=0.10; 0.33; 0.54, and for 3 pitch angles, two of them at values lower than the static stall angle of incidence, the third at a higher value. During the tests the tip Mach number was maintained constant at M(sub tip)=0.22. Results obtained on the velocity components have allowed characterizing the different aspects of the BL. At low incidences, chordwise velocity profiles exhibit a turbulent behavior (po...
_______________________________________________________________________________________ Abstract ... more _______________________________________________________________________________________ Abstract The paper focuses on stereoscopic PIV-3C measurements performed to investigate the vortical flow generated in the wake of helmets dedicated to Time Trial (TT) stages. The objective is to characterize the wake flow of TT helmet shapes and to provide the characteristics of the wake generated by different streamlined helmet geometries. The study specifically aims to provide detailed flow databases on helmet wakes in order to improve our understanding to identify efficient factors that may provide an efficient drag force reduction. Experiments are carried out in the ISM wind tunnel at a freestream velocity close to 14 ms -1 . The use of a laser light technique does not allow testing on human and PIV measurements are thus performed on a rigid articulated mannequin (full scale 1/1) installed on the bicycle. The ensemble mannequin-bicycle is mounted on a force measurement platform in the wind t...
The present work is focused on the aerodynamic study of different parameters, including both the ... more The present work is focused on the aerodynamic study of different parameters, including both the posture of a cyclist's upper limbs and the saddle position, in time trial (TT) stages. The aerodynamic influence of a TT helmet large visor is also quantified as a function of the helmet inclination. Experiments conducted in a wind tunnel on nine professional cyclists provided drag force and frontal area measurements to determine the drag force coefficient. Data statistical analysis clearly shows that the hands positioning on shifters and the elbows joined together are significantly reducing the cyclist drag force. Concerning the saddle position, the drag force is shown to be significantly increased (about 3%) when the saddle is raised. The usual helmet inclination appears to be the inclination value minimizing the drag force. Moreover, the addition of a large visor on the helmet is shown to provide a drag coefficient reduction as a function of the helmet inclination. Present results...
Water science and technology : a journal of the International Association on Water Pollution Research, 2002
The Mid North Rivers Management Planning Project (MNRMPP) of the Environment Protection Agency, D... more The Mid North Rivers Management Planning Project (MNRMPP) of the Environment Protection Agency, Department for Environment and Heritage began as a response to community concerns regarding watercourse related issues in the Mid North of South Australia. In response to these concerns the MNRMPP project team developed rapid, cost effective methods to collect and assess data, establish collaborative partnerships with stakeholder organisations, ensure community involvement, and initiate mechanisms to sustain local involvement past the life of the project. Environmental water requirements were identified, along with key watercourse management issues; the integration of these two components of the study enabled more informed decision making regarding watercourse management within the study area. The integration of these components and the involvement of the community and stakeholders through all components of the project has resulted in a sense of ownership and an increase in awareness of w...
Topics: Bicycle. Abstract: During a time-trial (TT) stage on flat track at 50 Km.h-1, aerodynamic... more Topics: Bicycle. Abstract: During a time-trial (TT) stage on flat track at 50 Km.h-1, aerodynamic drag force represents 90% of the power developed by the runner (Belluye and Cid, 2001). Given the drag resistance impact on TT performances, aerodynamics optimization of posture ...
Abs tract This paper concerns a collaborative research work between DLR of Göttingen and LABM of ... more Abs tract This paper concerns a collaborative research work between DLR of Göttingen and LABM of Marseille which aims to create a new experimental data base characterizing the tilt-rotor wake and the associated vortex structures. This study will provide detai led flow data on the aerodynamic interactions causes which occur on a tilt-rotor aircraft including a rotor, a nacelle, a fixed wing and an e nd plate simulating the fuselage. Experiments have been performed in the LABM S1L wind-tunnel at 3 different flight configurations which correspond to hover, conversion and cruise flights. The stereoscopic PIV system generates an illuminating laser sheet in a Z-plane normal to the uniform free stream velocity U8. PIV measurements have been performed at different Z-planes distributed at different distance downstream the rotor (in the wake region between the rotor and the wing and above the fixed wing) in both the conversion and cruise flight configurations and for different parametric cond...
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Papers by Daniel Favier