Turbulence measurements in a merged jet from two opposing curved wall jets

Abstract

Abstract. A two-dimensional flow generated by the interaction of two opposing, symmetric curved wall jets is investigated experimentally. The overall flow field can be divided into the curved wall jet region, the interaction region, and the merged jet region; thus, the results of the measurement are discussed to characterize these three distinct regions. For the curved wall jet region, the Reynolds stress distribution, the correlation coefficient, fiu v', and the ratio of normal stresses, v2/u 2, are presented and the effects of curvature and adverse pressure gradient on these distributions are discussed. The Reynolds stress distributions in the interaction region are analyzed in detail to illuminate the negative production of the turbulent kinetic energy. The developing jet in this region is found to accelerate owing to the very high pressure arising from the collision of the two wall jets. A counter-gradient shear flow situation is also observed in this interacting region. Measured data in the merged jet region are often compared to those of plane jets and the development of the merged jet is discussed in that respect. The spreading rate of the present merged jet is found to be much larger than that of the plane jets. To account for the larger spreading rate, the intermittency distribution is also investigated.

Reduced basis simulations as a tool for generating turbulent inlet‐data for two opposing jets

“…Here, b is the x position where the merged jet mean velocity W is half the centreline velocity. The growth rate db=dz is found to be 0.125, which is less than the value of 0.15 reported in Reference [5] and the value of approximately 0.2 found in Reference [4]. The reason might be that the boundary conditions used here are very regular such that apping of the jet is not easily triggered.…”

“…Figure 5 shows mean velocity W , rms-proÿles and turbulent shear-stress uw of the merged jet. The results are compared with experimental data from two opposing curved wall jets [5] and two opposing plane wall jets [4]. Considering the dissimilarities of the colliding ows, the level of turbulence intensities after interaction is remarkably similar.…”

“…The turbulence in such ows has been shown awkward to accurately model [3]. Experimental studies of the outwash ow arising from two colliding turbulent jets show very high turbulence intensities in the stagnation region [4,5]. Another interesting feature is that the fountain jet has growth rates considerably larger than the growth rates found in free planar jets [6].…”

Direct numerical simulation of two opposing wall jets

“…Figure 11 shows the mean velocities ͗U͘ and ͗W͘, turbulent shear stress ͗uw͘ and ͗uw͘ / ͑u rms w rms ͒͒ of the fountain jet. The results are compared with experimental data from two opposing curved wall jets, 22 from two opposing plane wall jets, 21 and measurements in the self-similar region of a conventional plane jet. 24 When comparing with the opposing jet experiments ͑z / z max ͒ DNS Ϸ͑z / z max ͒ experiment , where z max is the distance from the wall to where the mean velocity ͗W͘ reaches its maximum.…”

“…20 Experimental studies of the outwash flow arising from two colliding turbulent jets show exceptionally high turbulence intensities in the stagnation region. 4,21,22 Interestingly, the fountain jet has growth rates considerably larger than the growth rates found in free planar jets. [23][24][25] The objective is to study the dynamics of this particular flow and to produce turbulence statistics and kinetic energy budgets which hopefully can serve as a benchmark test for turbulence modelers.…”