A study of the constant-temperature hot-wire anemometer

Perry, A. E.; Morrison, Gerald L.

doi:10.1017/s0022112071001241

Cited by 89 publications

(44 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Details of the anemometer design are given in Perry 27 and Perry and Morrison. 28 The single-normal hot-wire probe used is a boundary layer type probe-body geometry 55P15 from Dantec, while the cross-wire probe is 55P61 from the same manufacturer. Both probe sensors consist of 5 µm diameter platinum filament sensors, formed from Wollaston wire with an etched length l = 1 mm.…”

Section: Velocity Measurementsmentioning

confidence: 99%

Roll-modes generated in turbulent boundary layers with passive surface modifications

Nugroho

Kevin²,

Monty

et al. 2014

52nd Aerospace Sciences Meeting

View full text Add to dashboard Cite

A unique class of directional surfaces arranged in a converging-diverging (herringbone) pattern are studied experimentally in a zero pressure gradient turbulent boundary layers. Hot-wire measurements using both single and cross-wire show that these small surfaces are able to generate large-scale counter rotating roll-modes/vortices within the turbulent boundary layer, resulting in dramatic spanwise variation in the boundary layer thickness δ (50% variation for the strongest case). The results reveal that above the converging region, the local mean velocity decreases while the turbulence intensity increases, resulting in locally thicker boundary layer. Over the diverging region, the opposite situation occurs, where the mean velocity increases and the turbulence intensity decreases, resulting in a locally thinner boundary layer. The strong perturbation effect from these surfaces to the overall flow dynamics seems unusual, considering that their peak-to-trough height is approximately only 1% of the boundary layer thickness. This study, also investigates the behavior of the large-scale counter-rotating roll-modes when the surface reverts from the herringbone pattern back to the smooth wall, to see how far they persist over the smooth wall. Our preliminary results show that the roll-modes above the smooth wall still persist even at 40δ downstream. The results of this study show that the herringbone surface roughness pattern can act as a novel method of generating counter rotating roll-modes (vortices) for flow control purposes in various engineering applications. Nomenclaturex Streamwise direction/distance, m y Spanwise direction/distance, m z Wall-normal direction/distance, m U Mean streamwise velocity, m/s V Mean spanwise velocity, m/s W Mean wall-normal velocity, m/s U ∞ Freestream velocity, m/s U τ Skin friction velocity, m/s U sa Spanwise averaged mean velocity, m/s δ Boundary layer thickness, m δ s Boundary layer thickness over smooth wall, m δ r Boundary layer thickness over rough surface, m δ sa Boundary layer thickness averaged over one spanwise wavelength, m δ rs Boundary layer thickness averaged over one spanwise wavelength of rough to smooth case, m Downloaded by KUNGLIGA TEKNISKA HOGSKOLEN KTH on July 30, 2015 | http://arc.aiaa.org |

show abstract

Section: Velocity Measurementsmentioning

confidence: 99%

Roll-modes generated in turbulent boundary layers with passive surface modifications

Nugroho

Kevin²,

Monty

et al. 2014

52nd Aerospace Sciences Meeting

View full text Add to dashboard Cite

show abstract

“…De acordo com Davis (1970); Perry & Morrison (1971); Weidman & Browand (1975); Ower & Pankhurst (1977); Lomas (1986) ;Miller et al (1987); Pearcy et al (1989); Watmuff (1995) o anemômetro de fio quente de temperatura constante caracterizase pelo aquecimento do sensor por determinada corrente elétrica, seu resfriamento devido às trocas de calor com o fluido e mantença da resistência e temperatura média do sensor a valores praticamente constantes, por um sistema de realimentação, que fornece a corrente elétrica de aquecimento, variável com a velocidade do fluido (Figura 5).…”

Section: Figura 3 Ponte De Wheatstoneunclassified

Desenvolvimento E Avaliação De Um Anemômetro De Fio Quente Operando À Temperatura Constante

Sampaio

Passos²,

Dias³

et al. 1998

Rev. bras. eng. agríc. ambient.

View full text Add to dashboard Cite

RESUMOEsta pesquisa teve como objetivo desenvolver um anemômetro de fio quente para operar à temperatura constante usando-se, como elemento sensível, filamento de tungstênio de lâmpada incandescente, como braço da ponte de Wheatstone. Um circuito eletrônico foi construído e testado, permitindo controlar a tensão no sensor e restaurar o equilíbrio da ponte de Wheatstone em processos de troca de calor pelo sensor. Os resultados mostraram que a corrente elétrica e a temperatura de operação do sensor, mediante compromisso entre vida útil e sensibilidade, foram de 160mA e 140°C, respectivamente; a calibração com o sensor no circuito ponte de Wheatstone mostrou sensibilidade para medir a velocidade do ar no intervalo de 0,00 e 5,00m.s -1 e que o circuito eletrônico apresentou saturação para velocidades do ar inferiores a 0,50m.s ABSTRACTThis research was carried out with the purpose of developing a hot-wire anemometer operating at constant temperature, using as a sensitive element a tungsten filament fan incandescent lamp as a Wheatstone bridge arm. An eletronic circuit was constructed and tested to control the voltage in the sensor and to restore the equilibrium of the Wheatstone bridge in the transfer of heat by the sensor. The results showed that the sensor's eletrical current and temperature of operation, considering useful life and sensibility, was 160mA and 140 o C, respectively. The calibration with the sensor in the Wheatstone bridge circuit showed sensibility to measure the air velocity in the interval between 0.00 and 5.00m.s -1. It also showed that this eletronic circuit presented saturation in measuring the air velocity lower than 0.50m.s INTRODUÇÃOAnemômetros são instrumentos usados para medidas de velocidade de ar e de outros fluidos; existem vários com características de construção e operação diferentes. Para baixas velocidades, os anemômetros que operam no princípio das trocas de calor são os mais indicados e seu funcionamento se baseia nas trocas de calor entre sensor aquecido e o fluido, provocando alteração da resistência elétrica do sensor, que pode ser correlacionada à velocidade do fluido. Estes anemômetros

show abstract

“…This makes the hot-wire anemometer particularly attractive for high-frequency turbulence measurements. Dynamic analysis of the CTA Bridge has been attempted by several authors (in particular Freymuth (1967Freymuth ( , 1977 and Perry and Morrison (1971)) with varying degrees of success. Apart from the complex thermal and electrical interactions within the bridge; the system is inherently non-linear, as highlighted by Freymuth (1979 For any quantitative work, it is essential to calibrate the probes individually.…”

Section: Cta Bridge Operationmentioning

confidence: 99%

“…Weighting factors are included to give a curve-fitting accuracy approximating to a constant percentage of reading.~r Constant-temperature anemometry is a well-established technique for investigating turbulent flow. Although the method is now venerable, detailed points of design still generate controversy (Freymuth, 1967, 19777;Perry and Morrison, 1971). …”

mentioning

confidence: 99%

A microprocessor-based automatic polynomial lineariser for constant-temperature anemometry systems

Marlowe¹

1981

Transactions of the Institute of Measurement and Control

View full text Add to dashboard Cite

The paper describes a microprocessor-based lineariser module which automatically computes the coefficients, offset, and gain settings required for an integral wideband polynomial lineariser. An iterative technique is used whereby the aggregate residual-squared error between the normalised input data and the generated 4th-order polynomial converges to a minimum. Weighting factors are included to give a curve-fitting accuracy approximating to a constant percentage of reading.~r s~b~~s used air rth coefficient in the polynomial approximation A 1 ~ ) temperature-dependent constant in the heat-transfer law B ( ) constant in the heat-transfer law E_4 bridge output (volts) E~,~,~,~ root-mean-square error f ( ) function to be approximated F ( ) generalised function gr rth value for the gradient G ( ) generalised function H~ rate of heat transfer to the fluid (watts) i an index j an index c an index n degree of the polynomial N data point number r an index R () residual error Rf wire resistance at fluid temperature (S2) R~, wire resistance at operating temperature (E2)

show abstract

A study of the constant-temperature hot-wire anemometer

Cited by 89 publications

References 2 publications

Roll-modes generated in turbulent boundary layers with passive surface modifications

Roll-modes generated in turbulent boundary layers with passive surface modifications

Desenvolvimento E Avaliação De Um Anemômetro De Fio Quente Operando À Temperatura Constante

A microprocessor-based automatic polynomial lineariser for constant-temperature anemometry systems

Contact Info

Product

Resources

About