Engineering and Physical Science Research Council (EPSRC) / This thesis describes the development of the two-frequency Planar Doppler Velocimetry (2n-PDV) flow measurement technique. This is modification of the Planar Doppler Velocimetry (PDV) technique that allows the measurement of up to three components of the flow velocity across a plane defined by a laser light sheet. The 2n-PDV technique reduces the number of components required to a single CCD camera and iodine cell from the two CCDs in conventional PDV. This removes the error sources associated with the misalignment of the two camera images and polarisation effects due to the beam splitters used in conventional PDV. The construction of a single velocity component 2n-PDV system is described and measurements made on the velocity field of a rotating disc and an axisymmetric air jet. The system was then modified to make 3D velocity measurements using coherent imaging fibre bundles to port multiple views to a single detector head. A method of approximately doubling the sensitivity of the technique was demonstrated using the measurements made on the velocity field of the rotating disc and was shown to reduce the error level in the final orthogonal velocity components by ~40 to 50%. Error levels of between 1.5ms-1 and 3.1ms-1 depending upon observation direction are demonstrated for a velocity field of ±34ms-1. The factors that will influence the selection of a viewing configuration when making 3D PDV measurements are then investigated with the aid of a computer model. The influence of the observation direction, the magnitude of the flow velocity, and the transformation to orthogonal velocity components are discussed. A new method using additional data in this transformation is presented and experimental results calculated using four-measured velocity components are compared to those found conventionally, using only three components. The inclusion of additional data is shown to reduce the final error levels by up to 25%.

This thesis describes the development of the two-frequency Planar Doppler Velocimetry (2n-PDV) flow measurement technique. This is modification of the Planar Doppler Velocimetry (PDV) technique that allows the measurement of up to three components of the flow velocity across a plane defined by a laser light sheet. The 2n-PDV technique reduces the number of components required to a single CCD camera and iodine cell from the two CCDs in conventional PDV. This removes the error sources associated with the misalignment of the two camera images and polarisation effects due to the beam splitters used in conventional PDV. The construction of a single velocity component 2n-PDV system is described and measurements made on the velocity field of a rotating disc and an axisymmetric air jet. The system was then modified to make 3D velocity measurements using coherent imaging fibre bundles to port multiple views to a single detector head. A method of approximately doubling the sensitivity of the technique was demonstrated using the measurements made on the velocity field of the rotating disc and was shown to reduce the error level in the final orthogonal velocity components by ~40 to 50%. Error levels of between 1.5ms-1 and 3.1ms-1 depending upon observation direction are demonstrated for a velocity field of ±34ms-1. The factors that will influence the selection of a viewing configuration when making 3D PDV measurements are then investigated with the aid of a computer model. The influence of the observation direction, the magnitude of the flow velocity, and the transformation to orthogonal velocity components are discussed. A new method using additional data in this transformation is presented and experimental results calculated using four-measured velocity components are compared to those found conventionally, using only three components. The inclusion of additional data is shown to reduce the final error levels by up to 25%.

The noise emitted from tactical supersonic aircraft presents a dangerous risk of noise-induced hearing loss for personnel who work near these jets. Although jet noise has many interacting features, large-scale turbulent structures are believed to dominate the noise produced by heated supersonic jets. To characterize the unsteady behavior of these large-scale turbulent structures, which can be correlated over several jet diameters, a velocimetry technique resolving a large region of the flow spatially and temporally is desired. This work details the development of time-resolved Doppler global velocimetry (TRDGV) for the study of large-scale turbulence in high-speed flows. The technique has been used to demonstrate three-component velocity measurements acquired at 250 kHz, and an analysis is presented to explore the implications of scaling the technique for studying large-scale turbulent behavior. The work suggests that the observation of low-wavenumber structures will not be affected by the large-scale measurement. Finally, a spatiotemporally-resolved measurement of a heated supersonic jet is achieved using large-scale TRDGV. By measuring a region spanning several jet diameters, the lifetime of turbulent features can be observed. The work presented in this dissertation suggests that TRDGV can be an invaluable tool for the discussion of turbulence with respect to aeroacoustics, providing a path for linking the flow to far-field noise. / Doctor of Philosophy / During takeoff, the intense noise emitted from tactical supersonic aircraft exposes personnel to dangerous risks of noise-induced hearing loss. In order to develop noise-reduction techniques which can be applied to these aircraft, a better understanding of the links between the jet flow and sound is needed. Laser-based diagnostics present an opportunity for studying the flow-field through time and space; however, achieving both temporal and spatial resolution is a technically challenging task. The research presented herein seeks to develop a diagnostic technique which is optimized for the study of turbulent structures which dominate jet noise production. The technique, Doppler global velocimetry (DGV), uses the Doppler shift principle to measure the velocity of the flow. First, the ability of DGV to measure the three orthogonal components of velocity is demonstrated, acquiring data at 250 kHz. Since turbulent structures in heated jets can be correlated over long distances, the effects on measurement error due to a large field-of-view measurement are investigated. The work suggests that DGV can be an invaluable tool for the discussion of turbulence and aeroacoustics, particularly for the consideration of full-scale measurements. Finally, a large-scale velocity measurement resolved in time and space is demonstrated on a heated supersonic jet and used to make observations about the turbulence structure of the flow field.

Repairs and modifications were made to a flow velocity measurement system designed to measure a planar area of unsteady three component velocities in a single realization using a velocity measurement technique referred to as Doppler Global Velocimetry (DGV). Several hardware components in the system were modified and new hardware was added. Significant improvements were made to the procedures used in acquiring DGV data as well as the procedures used in reducing the acquired DGV data. Though hardware problems were encountered, successful iodine cell calibrations were acquired and attempts were made to acquire DGV velocity data from a calibration wheel and in the wake of a 6:1 prolate spheroid. These attempts were hampered by poor performance of the Nd:YAG laser and one of the digital cameras used in this research. While the magnitudes of the velocities acquired from the calibration wheel were noticeably higher than those calculated from the angular velocity and large fluctuations were present in these reduced velocities, the general trends measured by the VT DGV system matched those calculated from the angular velocity. The attempt to acquire flow field data in the wake of a 6:1 prolate spheroid model was unsuccessful due to insufficient seed particle density in the area where data were to be obtained. The results of this research indicate that while significant improvements have been made to the system, there are still some significant problems to overcome. / Master of Science

The development of aerodynamic boundary layers on wind turbine blades is an important consideration in their performance. It can be quite challenging to replicate full scale conditions in laboratory experiments, and advanced diagnostics become valuable in providing data not available from traditional means. A new variant of Doppler global velocimetry (DGV) known as cross-correlation DGV is developed to measure boundary layer profiles on a wind turbine blade airfoil in the large scale Virginia Tech Stability Wind Tunnel. The instrument provides mean velocity vectors with reduced sensitivity to external conditions, a velocity measurement range from 0ms^-1 to over 3000ms^-1, and an absolute uncertainty. Monte Carlo simulations with synthetic signals reveal that the processing routine approaches the Cramér-Rao lower bound in optimized conditions. A custom probe-beam technique is implanted to eliminate laser flare for measuring boundary layer profiles on a DU96-W-180 wind turbine airfoil model. Agreement is seen with laser Doppler velocimetry data within the uncertainty estimated for the DGV profile. Lessons learned from the near-wall flow diagnostics development were applied to a novel benchmark model problem incorporating the relevant physical mechanisms of the high amplitude periodic turbulent flow experienced by turbine blades in the field. The model problem is developed for experimentally motivated computational model development. A circular cylinder generates a periodic turbulent wake, in which a NACA 63215b airfoil with a chord Reynolds number Re_c = 170, 000 is embedded for a reduced frequency k = (pi)fc/V = 1.53. Measurements are performed with particle image velocimetry on the airfoil suction side and in highly magnified planes within the boundary layer. Outside of the viscous region, the Reynolds stress profile is consistent with the prediction of Rapid Distortion Theory (RDT), confirming that the redistribution of normal stresses is an inviscid effect. The fluctuating component of the phase- averaged turbulent boundary layer profiles is described using the exact solution to laminar Stokes flow. A phase lag similar to that in laminar flow is observed with an additional constant phase layer in the buffer region. The phase lag is relevant for modeling the intermittent transition and separation expected at full scale. / Ph. D.

Supersonic hot jet noise causes significant hearing impairment to the military workforce and results in substantial cost for medical care and treatment. Detailed insight into the turbulence structure of high-speed jets is central to understanding and controlling jet noise. For this purpose a new instrument based on the Doppler global velocimetry technique has been developed. This instrument is capable of measuring three-component velocity vectors over ex-tended periods of time at mean data-rates of 100 kHz. As a demonstration of the applicability of the time-resolved Doppler global velocimetry (TR-DGV) measurement technique, statistics of three-component velocity measurements, full Reynolds stress tensors and spectra along the stream-wise direction in a cold, supersonic jet at exit Mach number Mj = 1.4 (design Mach number Md = 1.65) are presented. In pursuance of extending the instrument to planar op- eration, a rapid response photomultiplier tube, 64-channel camera is developed. Integrating field programmable gate array-based data acquisition with two-stage amplifiers enables high-speed flow velocimetry at up to 10 MHz. Incor- porating this camera technology into the TR-DGV instrument, an investigation of the perfectly expanded supersonic jet at two total temperature ratios (TTR = 1.6 and TTR = 2.0) was conducted. Fourth-order correlations which have direct impact on the intensity of the acoustic far-field noise as well as convective velocities on the lip line at several stream-wise locations were obtained. Comprehensive maps of the convective velocity and the acoustic Mach number were determined. The spatial and frequency scaling of the eddy convective velocities within the developing shear layer were also investigated. It was found that differences in the radial diffusion of the mean velocity field and the integral eddy convective velocity creates regions of locally high convective Mach numbers after the potential core. This, according to acoustic analogies, leads to high noise radiation efficiency. The spectral scaling of the eddy convec- tive velocity indicates intermittent presence of large-scale turbulence structures, which, coupled with the emergence of Mach wave radiation, may be one of the main driving factors of noise emission observed in heated supersonic jets. / Ph. D.

Jet noise has been a growing concern in recent years due to the costs associated with hearing loss of United States service members. Jet noise is also becoming more of a concern due to the rise of civilian complaints regarding the noise of jets near civilian and military air stations. One source of noise generation is from packets of air called eddies, which move with a convection velocity Uc. The current work seeks to expand upon the understanding of jet noise by collecting data using Time-resolved Doppler global velocimetry (TR-DGV) from regions of the jet known to produce high levels of acoustic radiation. Past experiments in studying convection velocity are reviewed based on the technique for obtaining the velocities. To add to these experiments, the current work analyzes data obtained using TR-DGV applied to a perfectly expanded Mach 1.65 flow with total temperature ratio (TTR) equal to 1. Additional measurements were obtained on a Mach 1.5 nozzle operated at a slightly over expanded condition and at TTR = 2. The cold jet flow is compared to the past experiments on unheated jets and demonstrates good agreement with respect to normalized convection velocities based on the jet exit speed. The data is then compared to past experiments conducted on the same nozzle at heated conditions. Shadowgraph imaging is used as a qualitative tool to locate shock cells within the jet plume. TR-DGV data from near the lipline (r = 0.5D) is axially aligned with the shadowgraph images to demonstrate that the shock structure within the potential core causes detectable variations in the scalar convective velocity. Additionally, it is shown that in the heated and unheated Mach 1.65 jet and the over expanded heated Mach 1.48 jet that the convection velocity does increase beyond the potential core. The Mach 1.48 jet is also compared to mean velocities obtained using Particle Image Velocimetry and found that the convective and mean velocities were only similar in some regions of the jet. A discussion is provided on suggestions of future work on where to obtain data within the jet plume and how to collect the data using current capabilities. Suggestions are also provided for improving data quality in future experiments, as well as ideas for future investigations into convection velocity along the length of the jet plume using TR-DGV. / Master of Science / Jet noise has been a growing concern in recent year due to the costs associated with hearing loss of United States service members. Additionally, many civilians complain about the noise of aircraft flying both out of military facilities and commercial airports. One source of noise generation is from packets of air called eddies which move with a convection velocity. Researchers have identified that by affecting the convection velocities of these eddies, there is a larger benefit than other traditional methods such as engine chevrons. The current work summarizes techniques used to investigate convective velocity as well as to provide evidence for other unconfirmed theories. This study focuses on using a laser-based technique to obtain data within the flow of an unheated supersonic jet. An unheated jet is studied to allow for easy comparison to other experiments that have used different diagnostic techniques. Additionally, this case is studied to complete a set of experiments that were previously conducted on the same nozzle so that there is a true base-line or “control” case for future work. Later in this paper, analysis will be done to show how shocks within the jet affect the convective velocity. A combination of both quantitative and qualitative efforts are performed to accomplish this. Additionally, it will be shown that after the potential core of the jet breaks down, there is an increase in the local convective velocity in this region immediately after the potential core. Finally, a brief summary will be given and suggestions for future work will be presented.

Die Reduzierung des Ressourcenverbrauchs und der Lärm- und Schadstoffemissionen von technischen Strömungsprozessen wie Verbrennungs- und Einspritzvorgängen ist von hoher gesellschaftlicher Bedeutung und erfordert ein tieferes Verständnis der auftretenden Strömungsphänomene. Hierfür ist die messtechnische Erfassung der Strömungen notwendig, wobei insbesondere die Strömungsgeschwindigkeit von hohem Interesse ist. Strömungsgeschwindigkeitsmessungen in dynamischen oder reaktiven Fluiden stellen jedoch hohe Anforderungen an die eingesetzte Messtechnik. Um Strömungsoszillationen und instationäre Phänomene mit kurzen Zeitskalen erfassen zu können, muss eine Messung simultan dreikomponentig und mit einer hohen Messrate von 100 kHz oder mehr erfolgen. Zur Analyse komplexer und kleinskaliger Geschwindigkeitsfelder ist eine bildgebende oder volumetrische Messung mit einer hohen örtlichen Auflösung wünschenswert. Momentan verfügbare Messsysteme genügen bisher nicht allen genannten Anforderungen. Das Ziel dieser Arbeit ist daher die Entwicklung, Charakterisierung und Qualifizierung eines geeigneten Systems zur zeitaufgelösten Erfassung instationärer Strömungsprozesse in hochdynamischen und reaktiven Fluiden. Einen für diese Zwecke vielversprechenden Ansatz stellt die Doppler-Global-Velozimetrie (FM-DGV) dar, da diese eine berührungslose Messung mit hoher Messrate gestattet und prinzipiell auch dreikomponentige und volumetrische Messungen ermöglicht. Daher erfolgte die Entwicklung und Realisierung eines simultan dreikomponentigen FM-DGV-Systems und eines FM-DGV-Systems zur bildgebenden und volumetrischen Messung. Die aufgebauten Systeme wurden hinsichtlich ihrer Geschwindigkeitsmessunsicherheit charakterisiert. Hierbei konnte gezeigt werden, dass die resultierenden Messunsicherheiten hinreichend klein sind und der Einfluss von Brechungsindexfluktuationen auf die Messunsicherheit vernachlässigt werden kann. Die Analyse der Messunsicherheiten aufgrund von Strömungsgeschwindigkeits- und Streulichtleistungsfluktuationen erfolgte mittels eines modellbasierten Ansatzes. Dabei wurde gezeigt, dass Streulichtleistungsfluktuationen einen dominanten Beitrag zum Messunsicherheitsbudget leisten können. Um die Eignung für die simultan dreikomponentige Messung mit hoher Messrate zu demonstrieren, wurden Messungen an einem Bias-Flow-Liner (BFL) durchgeführt. Dabei gelang erstmals an einem BFL die Untersuchung des Leistungsdichtespektrums in kartesischen Koordinaten und der Nachweis eines breitbandigen Energietransfers von Energie der Schallanregung hin zur kinetischen Energie der Strömung. Zur Demonstration der Messung in reaktiven Fluiden wurde ein drallstabilisierter Gasbrenner untersucht, wie er in stationären Gasturbinen und Flugzeugtriebwerken eingesetzt wird. Hierbei konnte eine thermo-akustische Wechselwirkung zwischen der Wärmefreisetzungsrate und dem Druck nachgewiesen werden und es zeigte sich ein Zusammenhang zwischen den lokalen Geschwindigkeitsoszillationen innerhalb der Flamme und den globalen Schalldruckemissionen. Durch die bildgebende, zeit- und ortsaufgelöste Messung mit hoher Messrate konnten zudem erstmals instationäre Phänomene der Strömungsgeschwindigkeit im düsennahen Bereich einer Hochdruck-Einspritzdüse ohne Seedingzufuhr vermessen werden. Diese Entwicklungen ermöglichen weitere Untersuchungen zum stabileren Betrieb von Gasbrennern mit mageren Gemischen, ein tieferes Verständnis der Dämpfungsmechanismen an BFL und die Optimierung des Einspritzvorganges in Motoren. Somit kann perspektivisch ein Beitrag zum ressourcenschonenden, umweltfreundlichen und leisen Betrieb von technischen Strömungsmaschinen wie Flugzeugtriebwerken, stationären Gasturbinen und Verbrennungsmotoren geleistet werden. / The reduction of the consumption of resources and the noise and polluting emissions of technical flow processes such as combustion and injection processes is of high social relevance and requires a deeper understanding of the occurring flow phenomena. For this purpose the metrological acquisition of the flows is necessary, whereat especially the flow velocity is of high interest. However, flow velocity measurements in dynamic or reactive fluids make great demands on the engaged measurement techniques. In order to resolve velocity oscillations or unsteady phenomena with short timescales a simultaneous three component measurement with a high measurement rate of 100 kHz or more is required. To analyze complex and small-scale velocity fields an imaging or volumetric measurement with a high spatial resolution is desired. Currently available measurement systems do not fulfill all these requirements. Hence, the goal of this work is the development, characterization and qualification of a measurement system suitable for the temporally resolved acquisition of unsteady flow processes in highly dynamic and reactive fluids. For this purpose the Doppler global velocimetry with laser frequency modulation (FM-DGV) represents a promising approach, since it allows a contactless measurement with high measurement rate and in principle enables simultaneous three component and volumetric measurements. Hence, as a first step a simultaneous three component FM-DGV system and a FM-DGV system for imaging and volumetric measurements were developed. Subsequently, the realized systems were characterized regarding their velocity measurement uncertainty. It was shown, that the resulting measurement uncertainty is sufficiently small and that the influence of fluctuations of the refractive index on the measurement uncertainty can be neglected. The analysis of the measurement uncertainty due to fluctuations of the flow velocity and the scattered light power was conducted using a model-based approach. It was thereby shown, that fluctuations of the scattered light power can lead to a dominant term of the uncertainty budget. In order to demonstrate the suitability for simultaneous three component measurement with high measurement rate, measurements at a bias flow liner (BFL) were conducted. Thereby for the first time at a BFL it was possible to determine the power spectral density in Cartesian coordinates and to show the broadband energy transfer from the energy of the sound excitation to the kinetic energy of the flow. To demonstrate the measurement in reactive flows, a swirl-stabilized burner was investigated, as it is used in stationary gas turbines and airplane engines. It was possible to prove a thermo-acoustic interaction between the heat release rate and the pressure and to show a correlation between the local velocity oscillations within the flame and the global sound pressure emissions. By means of the imaging, temporally and spatially resolved measurement with high measurement rate it was furthermore possible to resolve unsteady phenomena in the near-nozzle region of a high-pressure injection nozzle without the addition of tracer particles. These developments allow further investigations regarding the stable operation of gas burners with lean mixtures, a deeper understanding of the damping effects at BFL and the optimization of injection processes in engines. Consequently, it is perspectively possible to contribute to the resource-efficient, environment-friendly and quiet operation of technical flow machines as aircraft engines, stationary gas turbines and combustion engines.

Die Reduzierung des Ressourcenverbrauchs und der Lärm- und Schadstoffemissionen von technischen Strömungsprozessen wie Verbrennungs- und Einspritzvorgängen ist von hoher gesellschaftlicher Bedeutung und erfordert ein tieferes Verständnis der auftretenden Strömungsphänomene. Hierfür ist die messtechnische Erfassung der Strömungen notwendig, wobei insbesondere die Strömungsgeschwindigkeit von hohem Interesse ist. Strömungsgeschwindigkeitsmessungen in dynamischen oder reaktiven Fluiden stellen jedoch hohe Anforderungen an die eingesetzte Messtechnik. Um Strömungsoszillationen und instationäre Phänomene mit kurzen Zeitskalen erfassen zu können, muss eine Messung simultan dreikomponentig und mit einer hohen Messrate von 100 kHz oder mehr erfolgen. Zur Analyse komplexer und kleinskaliger Geschwindigkeitsfelder ist eine bildgebende oder volumetrische Messung mit einer hohen örtlichen Auflösung wünschenswert. Momentan verfügbare Messsysteme genügen bisher nicht allen genannten Anforderungen. Das Ziel dieser Arbeit ist daher die Entwicklung, Charakterisierung und Qualifizierung eines geeigneten Systems zur zeitaufgelösten Erfassung instationärer Strömungsprozesse in hochdynamischen und reaktiven Fluiden. Einen für diese Zwecke vielversprechenden Ansatz stellt die Doppler-Global-Velozimetrie (FM-DGV) dar, da diese eine berührungslose Messung mit hoher Messrate gestattet und prinzipiell auch dreikomponentige und volumetrische Messungen ermöglicht. Daher erfolgte die Entwicklung und Realisierung eines simultan dreikomponentigen FM-DGV-Systems und eines FM-DGV-Systems zur bildgebenden und volumetrischen Messung. Die aufgebauten Systeme wurden hinsichtlich ihrer Geschwindigkeitsmessunsicherheit charakterisiert. Hierbei konnte gezeigt werden, dass die resultierenden Messunsicherheiten hinreichend klein sind und der Einfluss von Brechungsindexfluktuationen auf die Messunsicherheit vernachlässigt werden kann. Die Analyse der Messunsicherheiten aufgrund von Strömungsgeschwindigkeits- und Streulichtleistungsfluktuationen erfolgte mittels eines modellbasierten Ansatzes. Dabei wurde gezeigt, dass Streulichtleistungsfluktuationen einen dominanten Beitrag zum Messunsicherheitsbudget leisten können. Um die Eignung für die simultan dreikomponentige Messung mit hoher Messrate zu demonstrieren, wurden Messungen an einem Bias-Flow-Liner (BFL) durchgeführt. Dabei gelang erstmals an einem BFL die Untersuchung des Leistungsdichtespektrums in kartesischen Koordinaten und der Nachweis eines breitbandigen Energietransfers von Energie der Schallanregung hin zur kinetischen Energie der Strömung. Zur Demonstration der Messung in reaktiven Fluiden wurde ein drallstabilisierter Gasbrenner untersucht, wie er in stationären Gasturbinen und Flugzeugtriebwerken eingesetzt wird. Hierbei konnte eine thermo-akustische Wechselwirkung zwischen der Wärmefreisetzungsrate und dem Druck nachgewiesen werden und es zeigte sich ein Zusammenhang zwischen den lokalen Geschwindigkeitsoszillationen innerhalb der Flamme und den globalen Schalldruckemissionen. Durch die bildgebende, zeit- und ortsaufgelöste Messung mit hoher Messrate konnten zudem erstmals instationäre Phänomene der Strömungsgeschwindigkeit im düsennahen Bereich einer Hochdruck-Einspritzdüse ohne Seedingzufuhr vermessen werden. Diese Entwicklungen ermöglichen weitere Untersuchungen zum stabileren Betrieb von Gasbrennern mit mageren Gemischen, ein tieferes Verständnis der Dämpfungsmechanismen an BFL und die Optimierung des Einspritzvorganges in Motoren. Somit kann perspektivisch ein Beitrag zum ressourcenschonenden, umweltfreundlichen und leisen Betrieb von technischen Strömungsmaschinen wie Flugzeugtriebwerken, stationären Gasturbinen und Verbrennungsmotoren geleistet werden. / The reduction of the consumption of resources and the noise and polluting emissions of technical flow processes such as combustion and injection processes is of high social relevance and requires a deeper understanding of the occurring flow phenomena. For this purpose the metrological acquisition of the flows is necessary, whereat especially the flow velocity is of high interest. However, flow velocity measurements in dynamic or reactive fluids make great demands on the engaged measurement techniques. In order to resolve velocity oscillations or unsteady phenomena with short timescales a simultaneous three component measurement with a high measurement rate of 100 kHz or more is required. To analyze complex and small-scale velocity fields an imaging or volumetric measurement with a high spatial resolution is desired. Currently available measurement systems do not fulfill all these requirements. Hence, the goal of this work is the development, characterization and qualification of a measurement system suitable for the temporally resolved acquisition of unsteady flow processes in highly dynamic and reactive fluids. For this purpose the Doppler global velocimetry with laser frequency modulation (FM-DGV) represents a promising approach, since it allows a contactless measurement with high measurement rate and in principle enables simultaneous three component and volumetric measurements. Hence, as a first step a simultaneous three component FM-DGV system and a FM-DGV system for imaging and volumetric measurements were developed. Subsequently, the realized systems were characterized regarding their velocity measurement uncertainty. It was shown, that the resulting measurement uncertainty is sufficiently small and that the influence of fluctuations of the refractive index on the measurement uncertainty can be neglected. The analysis of the measurement uncertainty due to fluctuations of the flow velocity and the scattered light power was conducted using a model-based approach. It was thereby shown, that fluctuations of the scattered light power can lead to a dominant term of the uncertainty budget. In order to demonstrate the suitability for simultaneous three component measurement with high measurement rate, measurements at a bias flow liner (BFL) were conducted. Thereby for the first time at a BFL it was possible to determine the power spectral density in Cartesian coordinates and to show the broadband energy transfer from the energy of the sound excitation to the kinetic energy of the flow. To demonstrate the measurement in reactive flows, a swirl-stabilized burner was investigated, as it is used in stationary gas turbines and airplane engines. It was possible to prove a thermo-acoustic interaction between the heat release rate and the pressure and to show a correlation between the local velocity oscillations within the flame and the global sound pressure emissions. By means of the imaging, temporally and spatially resolved measurement with high measurement rate it was furthermore possible to resolve unsteady phenomena in the near-nozzle region of a high-pressure injection nozzle without the addition of tracer particles. These developments allow further investigations regarding the stable operation of gas burners with lean mixtures, a deeper understanding of the damping effects at BFL and the optimization of injection processes in engines. Consequently, it is perspectively possible to contribute to the resource-efficient, environment-friendly and quiet operation of technical flow machines as aircraft engines, stationary gas turbines and combustion engines.