Simultaneous Measurements of Velocity and Temperature in Nonisothermal Flows

Abstract

A two-wire probe technique has been developed for the simultaneous and continuous measurements of instantaneous velocity and temperature in nonisothermal flows. The equations of the thermal equilibrium of two adjacent fine wires, one hot and one only a little above the fluid temperature, are solved by employing analog technique, wherein not only the difference of the heat transfer coefficients between two wires but also their variations with both the velocity and temperature are taken into consideration. The measuring system proposed in this study is founded on fairly strict principles of analysis and, hence, provides automatic compensation even for very large amplitude velocity and temperature fluctuations over a frequency range of d-c to six kHz.

Effect of shear on Rayleigh-Taylor mixing at small Atwood number

“…Calibration is performed inside the tunnel using a wedge shaped block filled with fog particles and air (constant ρ ) with the same camera settings as the experiment. The [40] based on earlier work on simultaneous measurements of temperature and velocities by Hishida et al [42] and Vukoslavčević et al [43]. Temperature is used as a marker for density by gently heating one of the streams.…”

Development of High Precision Thermo-Anemometer

“…4・1 新遅延回路 プローブは，上下流に直径d =2.5μm の冷線及び5μm の熱線を平行に配置した (8) ．冷線後流の影響により冷・熱線間距離 は140d=0.35mm 以上必要とされる (11) ．本研究では，線間距離を1mm に設定した．凍結仮説 (12) から，線間距離L，流速U， 高精度温度流速計の開発 © 2013 The Japan Society of Mechanical Engineers 遅延時間Δ t の間にはΔt=L/U の関係が成立し (9) ，流速範囲U=1～12m/s で，遅延時間はΔ t =0.083ms～1ms となる．従来の 遅延回路 (9) Fig.8 Delay circuit . (a) Automatic DC adjustor circuit (b) Detailed schematic of the circuit θ( t)は OP Z2 で積分されΘ となり，OP Z1 でθ( t)-Θ としてゼロ補償 (13) される．次に入力スペックに合わせるため…”

Spatio-temporal turbulent structures of thermal boundary layer subjected to non-equilibrium adverse pressure gradient

“…Velocity and temperature fluctuations were simultaneously measured by the specially devised hot-and cold-wire technique (Hishida and Nagano, 1978;Nagano and Tsuji, 1994). The probe consisted of three fine wires, the upstream wire serving as the constant current cold-wire (platinum 90%/ rhodium 10%; diameter 0.625 lm; length 1.0 mm ' 18 in wall units; length-to-diameter ratio is 1600), and the two symmetrically bent V-shaped hot wires (Hishida and Nagano, 1988a,b; tungsten; diameter 5 lm; length 0.8 mm).…”