Turbulence measurements in shock-induced flows

Trolier, James W.; Duffy, Robert E.

doi:10.2514/3.9060

Cited by 28 publications

(7 citation statements)

References 18 publications

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“…It is also observed that the maximum amplification of turbulence intensity is observed around 3.1. Even though the turbulence intensity before interaction for different grid plates have good agreement with experimental results of Honkan et al [5] where the turbulence intensity were found 1.5-5 % but the amplification of turbulence intensity after the shock/turbulence interaction is slightly higher than the amplification, obtained by Troiler et al [6]. The amplification of turbulence intensity was approximately 3, which was found in the experimental works of Troiler et al [6].…”

Section: Numerical Setup and Specifica Tlonssupporting

confidence: 85%

Numerical and experimental investigation of shock/turbulence interaction by hotwire technique

Jinnah

Takayama

2011

2011 IEEE 3rd International Conference on Communication Software and Networks

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In the present paper, an experimental investigation has been carried out to observe the amplification of turbulence intensity after shocklturbulence interaction by hot-wire technique. The hot wires are installed in the wake of the turbulent grids to measure the turbulence fluctuations before and after the reflected shock wave interaction with the turbulent field. Due to different grid plates, different strengths of turbulent fields are found behind the transmitted shock wave. It is observed that the turbulence fluctuations for less open area of the grid plate are higher than the turbulence fluctuations for more open area of the grid plate. Numerical simulations are also conducted on the experimental results where grid plate of 49.5 % open area is used. It is observed that the average longitudinal velocity line for the experimental velocity data simulate with numerical results properly and in some places, 5-7 % deviations are observed with numerical results. All the simulation results indicate that the present code with turbulence model is working properly for its initial conditions. The wall pressure fluctuations are also measured experimentally and substantial amplification of pressure fluctuations is occurred after the shock/turbulence interaction.The rate of dissipation of turbulent kinetic energy (TKE) and the levels of length scales are determined numerically by using k-E turbulence model and it is observed that the rate of dissipation of TKE and the levels of length scales decrease after shock/turbulence interaction.

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Section: Numerical Setup and Specifica Tlonssupporting

confidence: 85%

Numerical and experimental investigation of shock/turbulence interaction by hotwire technique

Jinnah

Takayama

2011

2011 IEEE 3rd International Conference on Communication Software and Networks

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“…We measure instantaneous velocities by laser Doppler anemometry ͑LDA͒ instead of turbulent mass flux by hot wire. 6 Indeed, the presence of different viscosities and thermal conductivities in the mixing zone would have hindered the measurement of this latter quantity.…”

Section: ͓S1070-6631͑98͒00611-4͔mentioning

confidence: 99%

Velocity measurements in turbulent gaseous mixtures induced by Richtmyer–Meshkov instability

1998

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Instantaneous velocity measurements in a gaseous mixture arising from the shock wave-induced Richtmyer–Meshkov instability are conducted for the first time in a shock tube. Laser Doppler anemometry gives us the evolution of the axial velocity fluctuations of the mixing zone, before and after its interactions with reflected shock waves from the shock tube end wall. Experimental results demonstrate that a turbulent mixing zone is generated by the incident shock wave. Afterwards, the axial variance decreases before being amplified by the first reshock interaction through a baroclinic effect. Before the second reshock arrival, we measure once again a decrease of the turbulence level which is explained by both diffusion and dissipation.

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“…To determine the rms fluctuations of T, p, p, and u, these variables must be expressed in terms of the ''hot-wire variables" m 7m and T t 7T t . Equations (4-6) can be used to show that 5 (in shorthand) T t ) + (a (14) * !Tp = (a + /3)~2 [(/3m -T t )(am + r r ) + (a + 0)…”

Section: Analysis Of Hot-wire Datamentioning

confidence: 99%

“…(8-10) to obtain equations analogous toEqs. (11)(12)(13)(14)(15)(16).In the 1950's, Kovasznay developed a theory of compressible turbulence "modes" that provides a framework for development of hot-wire data reduction schemes. 6 He manipulated the Navier-Stokes equations to show that compressible turbulence can be decomposed into three quasi-independent fluctuating fields: sound, entropy, and vorticity.…”

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confidence: 99%

Improved method of analyzing hot-wire measurements in supersonic turbulence

Logan

1989

AIAA Journal

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IntroductionT HE hot-wire anemometer has been an important tool for turbulent flow measurement for several decades. Although it is being superceded by optical methods in some instances, there are still many applications for which the hot wire is the simplest and least expensive technique available. For this reason, and because so much data have been published that relies on hot-wire measurements, there is still considerable interest in understanding its behavior.In essence, the hot-wire anemometer measures the rate at which heat is transferred from a heated filament to the flow in which it is immersed. 1 This measurement, however, is not directly useful; fluid dynamicists are more interested in parameters such as root mean square fluctuations of temperature, density, velocity, or pressure, depending on the application. The technique that has been used most commonly to obtain these parameters requires neglect of pressure fluctuations. The inherent uncertainty of this method was calculated as a function of the magnitude of the pressure fluctuations by Johnson and Rose 2 for the case of negligible total temperature fluctuations. However, their analysis does not predict the probable direction of the error, nor does it address the more general case of nonadiabatic flows.The purpose of this Note is to introduce a novel method of analyzing hot-wire measurements that employs two new elements: first, the use of an independent measurement (or estimate) of rms pressure fluctuations; and second, an assumption concerning the special nature of the pressure fluctuation field.A hot-wire probe consists of a very fine metallic wire supported by two conducting prongs. The wire is heated by current passing through it and at the same time cooled by the fluid surrounding it. Analyzing the fluctuations in the voltage across the hot wire to obtain fluctuations in the flow variables is substantially simplified if the following conditions hold. First, the fluctuations of flow variables must be small compared to their time-averaged or ensemble-averaged values. Second, the wire must be oriented normal to the mean flow direction so that there are negligible contributions to the fluctuating signal from the transverse velocity components. As a result of these assumptions, the fluctuating component of the hot-wire voltage may be written 1where E is the hot-wire voltage, p is density, u is streamwise velocity, T t is the total (or stagnation) temperature, and the primes indicate small fluctuating components of the flow variables. The hot-wire sensitivities S p9 S u , and S T/ are defined by logarithmic derivatives, for example S u = [d(?nE)/d(?nu)] pyTt , and must be determined individually for each probe. The sensitivities are also functions of the wire operating temperature and, to some extent, the flow conditions. Note that Eq.(1) applies to both constant-temperature and constant-current modes of hot-wire operation. Hot-wire response may be simplified further if the Mach number is greater than 1.2, in which case 1 S p « S u = S m , where m = ...

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Turbulence measurements in shock-induced flows

Cited by 28 publications

References 18 publications

Numerical and experimental investigation of shock/turbulence interaction by hotwire technique

Numerical and experimental investigation of shock/turbulence interaction by hotwire technique

Velocity measurements in turbulent gaseous mixtures induced by Richtmyer–Meshkov instability

Improved method of analyzing hot-wire measurements in supersonic turbulence

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