Wall pressure field in the reattaching flow past deflectors—Part 2: with air injection

Narayanan, Rangaswami; Manafpour, Mohammad; Kavianpour, R.

doi:10.1680/wame.2001.148.1.39

Cited by 4 publications

(2 citation statements)

References 5 publications

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“…The average cavity pressure also increases significantly with increasing air inflow. Authors in [18] experimented in the effect of air injection on the wall pressure in the near field of deflectors placed in a duct. Various quantities of air have been injected just downstream of the ramps to form stationary air cavities.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software

Manafpour

Ebrahimnezhadian

2019

Eng. Technol. Appl. Sci. Res.

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The flow around the ramp embedded in a pressurized tunnel is divided into various zones downstream of the ramp, including the cavity and the main zone of flow above the shear layer. Ramp angle and height are parameters that affect the flow characteristics such as cavity length, velocity, and pressure coefficient immediately downstream of the ramp. In this study, OpenFOAM open source software and RNG K-ε turbulence model were used to simulate the flow around the under pressure tunnel ramp. In order to investigate the effect of the ramp geometry on the flow in various relative air discharges 0<β<10, the range of height and the angle of the ramp as 5<θ<20 and 0.1<tr/d<0.4 were developed and simulated. The correlation coefficient between the numerical and experimental results for the relative cavity length is in the range of 0.9377≤R2≤0.9722 that indicates proper agreement between results. The result of the research shows that in both cases of fixed height of ramp and increasing ramp angle, and fixed angle of the ramp and increasing ramp height, the values of the cavity length and maximum turbulence intensity increase, and the minimum pressure values at the cavity zone bed are decreased. But in both cases, the sensitivity of the three mentioned parameters is higher than the ramp height increment.

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Section: Introductionmentioning

confidence: 99%

Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software

Manafpour

Ebrahimnezhadian

2019

Eng. Technol. Appl. Sci. Res.

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“…This study shows how air injection affects the wall pressure field from that without air injection. Information concerning wall pressure is expected to be useful in the design of deflectors in tunnels and spillways (Narayanan, R., Manafpour, M., & Kavianpour, R., 2000). Computational Fluid Dynamics (CFD) has emerged as an important alternative in multiphase flow modelling.…”

Section: Figure 1 Flow Region Over Typical Aeratormentioning

confidence: 99%

Investigating the Effect of Aeration on the Flow Characteristics Around Under Pressure Tunnel Aerator Using Openfoam Open Source Software

Ebrahimnezhadian

Manafpour

2019

Journal of Applied Engineering Sciences

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The flow around the ramp embedded in a pressurized tunnel is divided into the various zones immediately downstream of the ramp, including the cavity and the main zone of flow above the shear layer. The aeration coefficient of the flow from the lower surface (inside the cavity)(βlower) is a function of non-dimensional numbers which aerator geometry parameters such as cavity length to ramp height Lc/tr is considered as one of the most important parameters. Therefore, in the present study, OpenFOAM software and RNG k-ε turbulence model were used to simulate the flow to study the aeration effect on flow characteristics, so the range of aeration coefficient as 0%<β<10% for four ramps with different tr/d ratios is Applied, then by increasing the aeration coefficient in the range of 0%<β<16%, The dependency range of relative Cavity length Lc/tr to (β) was evaluated. In order to verify performance of the numerical model, experimental results of Manafpour test were used. The results of the research indicate that in the aeration of flow with aerator ramp, the height of ramp has more influence relative to ramp angle. Moreover the main Effectiveness of the aeration coefficient on the cavity length was limited to air percent less than 10%.

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Investigation of Supercritical Flow and Shape of Flip Bucket Spillways on Coefficients of Dynamic Pressure

Vatandoust

Yarmohammadi

Kavianpour

2020

Journal of Energy Resources Technology

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Pressure fluctuation is one of the major turbulent flow characteristics. It may cause crucial problems for hydraulic structures. This research is based on experimental studies and it focuses on the measurements of pressure fluctuations along flip bucket spillways with different geometrical characteristics. The function of flip bucket spillway is discharging floods from reservoir dams which are energy storage sources measurements of dynamic pressures on three different models of flip buckets were performed for this investigation Pressure fluctuation of the flip buckets have been measured within a range of Froude numbers from 5 to 13 (Fr=ugy where u is flow speed and y is depth & g is 9.81 m/s2). Statistical characteristics of pressure fluctuations, the location and the values of maximum and minimum fluctuations have also supplemented the study. The results show that the coefficients of pressure fluctuations (Cp=RMS0.5u2g where RMS is Root mean square of pressure fluctuation, u is flow speed and g is 9.81 m/s2) reduce as the Froude number (Fr) of flow increases, except a maximum Froude number. Pressure coefficients increase along the flip bucket with incremental mutations in the transformation area of the flip bucket. In the middle part of the flip bucket spillway, pressure coefficient values decrease. Additionally, as Br (B is width of flip bucket and r is radius of flip bucket) ratio increases, pressure coefficients become larger and this process continues along the flip bucket.

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Wall pressure field in the reattaching flow past deflectors—Part 2: with air injection

Cited by 4 publications

References 5 publications

Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software

Investigating the Effect of Ramp Geometry on the Flow Characteristics Around Under Pressure Tunnel Aerator Using OpenFoam Open Source Software

Investigating the Effect of Aeration on the Flow Characteristics Around Under Pressure Tunnel Aerator Using Openfoam Open Source Software

Investigation of Supercritical Flow and Shape of Flip Bucket Spillways on Coefficients of Dynamic Pressure

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