Comparison of three types of swirling generators in coarse particle pneumatic conveying using CFD-DEM simulation

et al. 2019

Processes

The application of the hole cleaning device in downhole is a new technology that can improve the problem of cuttings accumulation in the annulus and improve the hole cleaning effect of the wellbore during drilling. In this paper, the Reynolds Averaged Navier-Stokes model, together with the Realizable k-ε turbulence model, are used to perform transient simulations. The effects of rotational speed, blade shape, and helical angle on the initial swirl intensity and its decay behavior along the flow direction are studied. The swirl number, the initial swirl intensity, the decay rate, the tangential velocity distribution, and the variation of pressure are analyzed. The results indicate that the swirl number of the swirl flow exponentially decays along the flow direction. The straight blade and V-shaped blade have different swirl flow induction mechanisms. Under specific drilling parameters, the critical helical angle is determined for both types of blades. When the selection of the helical angle is close to the critical value, the swirl flow will be close to the axial flow, which is of little help in hole cleaning. Moreover, the rotation direction of swirl flow will change when the helical angle exceeds the critical value.It is widely used in many industries to promote particle transportation by inducing swirl flow in the pipe. Swirl flow is the flow form with velocity components in both axial and tangential directions. It has wide potential in many industrial applications [5][6][7][8]. A variety of methods can be used to enhance the swirling effect of the fluid in the tube, including the spiral wall [9], tangential inlet [10], and blades induction [11,12]. Therefore, the swirl flow can be induced in the annulus by installing a hole cleaning device on the drill pipe, which can effectively improve the hole cleaning effect in the annulus. It is an ideal hole cleaning method, and one of its most significant benefits is that the rotational energy of the blade comes from the drill pipe and no extra energy is needed for the blade.Since the 2000s, a variety of hole cleaning devices have been designed, field tests have been carried out successfully, and satisfactory results have been obtained. Swietlik [13,14] first proposed the design concept of the straight-blade type hole cleaning device and the V-shaped-blade type hole cleaning device. During the process of application, the device can stir the cuttings that were adhered to the wall of the wellbore, so that the deposited cuttings particles can start to migrate again, which can effectively improve the performance of hole cleaning. Rodman et al. [15] reported a blade-type hole cleaning device. Field experiment shows that it can effectively solve the problems of low hole cleaning efficiency and poor wellbore quality. Puymbroeck et al. [16] introduced a compound hole cleaning device with double helix blade small joints. Laboratory experiments and field tests show that the device has an excellent cleaning ability of cuttings bed; besides, it can improve the efficiency of hole cl...

Section: Analysis Of the Effect Of The Rotational Speedsupporting

confidence: 92%

Numerical Simulation of the Effects of the Helical Angle on the Decaying Swirl Flow of the Hole Cleaning Device

et al. 2019

Processes

“…The decay of swirl intensity Sn induced by single-phase drilling fluid at a different blade rotational speed (100, 200, 300, and 400 rpm) along the axial direction is shown in Figure 3, with a blade angle of 0° and a blade height of h = 0.4 Dh. At different rotational speed, the swirl number Sn decay exponentially along the axial direction, which is consistent with the study from articles [24][25][26].…”

Section: Effect Of the Rotational Speed Of Hole Cleaning Performancesupporting

confidence: 90%

“…It can observe many flow details that are difficult to obtain in experiments. It has been successfully applied to the study of particle transport in swirling flow [24][25][26]. In this paper, a computational fluid dynamics (CFD) technique was used to establish a three-dimensional numerical model of the flow based on the experimental model of Han et al (2010).…”

Section: Introductionmentioning

confidence: 99%

Decaying Swirl Flow and Particle Behavior through the Hole Cleaning Device for Horizontal Drilling of Fossil Fuel

et al. 2019

Energies

The hole cleaning device is a powerful application which can effectively slow down the deposition of cuttings during drilling. However, in this complicated swirl flow created by the device, the decay of the swirl flow and the particle behavior are not evident yet. In this paper, the decay of the swirl flow and the particle behavior in the swirl flow field are studied by the Eulerian–Eulerian two-fluid model (TFM) coupled with the kinetic theory of granular flows (KTGF), and sliding mesh (SM) technique for simulating the fluid flow. The results show that the swirl intensity decays exponentially along the flow direction under laminar flow conditions. The swirl flow has a longer acting distance at a higher rotational speed, which can effectively slow down the deposition of cutting particles. The initial swirl intensity of swirl flow induced by the blades increases significantly with the increase of blade height and the decrease of the blade angle. The tangential velocity of the cutting particles in the annulus is more significant near the central region, gradually decreases toward the wall in the radial direction, and rapidly decreases to 0 at the wall surface. The decay rate is negatively correlated with the initial swirl intensity. The results presented here may provide a useful reference for the design of the hole cleaning device.

“…In recent years, innovative devices have emerged to optimize local facilities to induce swirl flow locally. These devices facilitate heat transfer enhancement, food and beverage industries, pneumatic/hydraulic conveying, and a broad spectrum of other engineering applications (Fokeer et al, 2009;Jafari et al, 2017;Tang et al, 2015;Zhou et al, 2016). They can improve energy efficiency and reduce additional energy consumption, effectively promoting energy conservation and emissions reduction.…”

Section: Introductionmentioning

confidence: 99%

“…The structure of a swirling flow depends on the methods and devices utilized to produce it. Coiled wires, twisted tapes, axial blades, internal spirals, tangential inlets, and radial blade cascades are the most popular types of swirl generators (Aydin et al, 2014;Taheran & Javaherdeh, 2019;Zhou et al, 2016). Among them, the multi-lobed swirl generator (MLSG) as a method for internal spiral induction is widely used due to its advantages of low cost, simple structure, and ready integration.…”

Section: Introductionmentioning

confidence: 99%

Numerical evaluation on the decaying swirling flow in a multi-lobed swirl generator

Engineering Applications of Computational Fluid Mechanics

et al. 2020

Accurate predictions of decaying swirling flow behavior in the multi-lobed swirl generator (MLSG) are essential for certain engineering applications. In this study, decaying swirling flow characteristics in an MLSG are examined using the Computational Fluid Dynamics (CFD) technique with a Reynolds stress turbulence model (RSM). The effects of different lobe numbers (n) and pitch length ratios (P/D) on swirl intensity, pressure drop, friction factor coefficient, and decay rate are observed with Reynolds number from 50,000 to 125,000. Combined with the pressure loss, the efficiency of swirl induction is evaluated by introducing a swirl effectiveness (SE) evaluation criterion. The initial swirl intensity is shown to first increases and then decreases as lobe number increases. The maximum value is obtained at lobe number n = 4. The pitch length ratios P/D corresponding to the optimal SE value obtained from different lobe also differ. The optimal SE value is achieved at n = 4 and P/D = 8. The friction factor ratio f s /f p decreases as pitch length ratio increases, but the decreasing trend decelerates over time. Correlations based on the numerical predictions of friction factor ratio f s /f p and decay rate β are presented accordingly.