### Abstract

An apparatus was designed and fabricated so that hot-wires could be used to obtain velocity measurements in an axisymmetric sudden expansion. The recirculating flow that exists in a sudden expansion and the directional insensitivity of hot-wires, required a device that would propel the hot-wires through the flow field faster than the flow was recirculating. Such a device, termed a 'flying' hot-wire system, literally collected data 'on the fly'. The sudden expansion facility has an expansion ratio of 3:1; and all of the measurements were at a Reynolds number of 41,000 based on bulk velocity and inlet pipe diameter. Significant simultaneous multi-point cross-wire measurements were obtained using this system. From these measurements, the mean velocities and normal stresses in all three directions as well as the dominant shear stress could be calculated as a function of streamwise distance. These quantities were used to perform a kinetic energy balance between the mean convection, production, turbulent diffusion and dissipation. From this energy balance, knowledge of the spatial variation of the isotropic dissipation was obtained. From these measurements, the velocity two-point correlation tensor, a quantity difficult to obtain in a separated flow, was calculated. In this paper, the two-point correlation tensor is utilized to calculate the integrated length scales in this flow geometry at several downstream locations.

Original language | English (US) |
---|---|

Pages (from-to) | 150-167 |

Number of pages | 18 |

Journal | Experimental Thermal and Fluid Science |

Volume | 18 |

Issue number | 2 |

DOIs | |

State | Published - 1998 |

Externally published | Yes |

### Fingerprint

### Keywords

- Flying-wire system
- Hot-wire anemometry
- Integrated length scale
- Mean velocities
- Normal stresses
- Shear stresses
- Spectral analysis
- Turbulent kinetic energy
- Two-point correlation tensor

### ASJC Scopus subject areas

- Fluid Flow and Transfer Processes
- Mechanical Engineering

### Cite this

**Flying hot-wire measurements in an axisymmetric sudden expansion.** / Cole, D. R.; Glauser, Mark N.

Research output: Contribution to journal › Article

*Experimental Thermal and Fluid Science*, vol. 18, no. 2, pp. 150-167. https://doi.org/10.1016/S0894-1777(98)10014-6

}

TY - JOUR

T1 - Flying hot-wire measurements in an axisymmetric sudden expansion

AU - Cole, D. R.

AU - Glauser, Mark N

PY - 1998

Y1 - 1998

N2 - An apparatus was designed and fabricated so that hot-wires could be used to obtain velocity measurements in an axisymmetric sudden expansion. The recirculating flow that exists in a sudden expansion and the directional insensitivity of hot-wires, required a device that would propel the hot-wires through the flow field faster than the flow was recirculating. Such a device, termed a 'flying' hot-wire system, literally collected data 'on the fly'. The sudden expansion facility has an expansion ratio of 3:1; and all of the measurements were at a Reynolds number of 41,000 based on bulk velocity and inlet pipe diameter. Significant simultaneous multi-point cross-wire measurements were obtained using this system. From these measurements, the mean velocities and normal stresses in all three directions as well as the dominant shear stress could be calculated as a function of streamwise distance. These quantities were used to perform a kinetic energy balance between the mean convection, production, turbulent diffusion and dissipation. From this energy balance, knowledge of the spatial variation of the isotropic dissipation was obtained. From these measurements, the velocity two-point correlation tensor, a quantity difficult to obtain in a separated flow, was calculated. In this paper, the two-point correlation tensor is utilized to calculate the integrated length scales in this flow geometry at several downstream locations.

AB - An apparatus was designed and fabricated so that hot-wires could be used to obtain velocity measurements in an axisymmetric sudden expansion. The recirculating flow that exists in a sudden expansion and the directional insensitivity of hot-wires, required a device that would propel the hot-wires through the flow field faster than the flow was recirculating. Such a device, termed a 'flying' hot-wire system, literally collected data 'on the fly'. The sudden expansion facility has an expansion ratio of 3:1; and all of the measurements were at a Reynolds number of 41,000 based on bulk velocity and inlet pipe diameter. Significant simultaneous multi-point cross-wire measurements were obtained using this system. From these measurements, the mean velocities and normal stresses in all three directions as well as the dominant shear stress could be calculated as a function of streamwise distance. These quantities were used to perform a kinetic energy balance between the mean convection, production, turbulent diffusion and dissipation. From this energy balance, knowledge of the spatial variation of the isotropic dissipation was obtained. From these measurements, the velocity two-point correlation tensor, a quantity difficult to obtain in a separated flow, was calculated. In this paper, the two-point correlation tensor is utilized to calculate the integrated length scales in this flow geometry at several downstream locations.

KW - Flying-wire system

KW - Hot-wire anemometry

KW - Integrated length scale

KW - Mean velocities

KW - Normal stresses

KW - Shear stresses

KW - Spectral analysis

KW - Turbulent kinetic energy

KW - Two-point correlation tensor

UR - http://www.scopus.com/inward/record.url?scp=0032447984&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0032447984&partnerID=8YFLogxK

U2 - 10.1016/S0894-1777(98)10014-6

DO - 10.1016/S0894-1777(98)10014-6

M3 - Article

VL - 18

SP - 150

EP - 167

JO - Experimental Thermal and Fluid Science

JF - Experimental Thermal and Fluid Science

SN - 0894-1777

IS - 2

ER -