Experimental and numerical study of the flow characteristics of a novel olive-shaped flowmeter (OSF)

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Highlights

  • A new type of differential pressure flowmeter with an olive-shaped flowmeter (OSF) was proposed.

  • Pressure loss of the proposed OSF was about 14.94% as that of the orifice plate flowmeter.

  • Relative pressure loss of the OSF decreases with the increase of the flow rate by up to 28%.

  • Flow characteristic of OSF is superior in streamline, pressure, and velocity distributions.

Abstract

A novel differential pressure flowmeter with an olive-shaped flowmeter (OSF) is proposed and investigated both experimentally and numerically. The streamline, pressure and velocity are obtained and numerically analysed. The results indicate that the proposed OSF exhibits less permanent pressure loss than the orifice plate flowmeter (OPF). The pressure also tends to be more stable in the OSF, which ensures high measurement accuracy and repeatability. The OSF is superior to the OPF in terms of relative pressure loss, streamline distribution, pressure distribution and velocity distribution. In the experiment, an oil pump transported diesel oil into the measurement pipe, through the check valve, filter, pressure-regulating container, and flow-regulating valve, before it was finally returned to the fuel tank. The experimental results showed that the pressure loss of the OSF was only about 14.94% of that of the OPF under the same conditions. The pressure loss curve of the OPF increased rapidly by up to 2,700 Pa with each 1 m3/h increase in the flow rate, whereas that of the OSF increased only slightly.

Introduction

The flow rate, which is widely recognised as a key parameter in most production and consumption processes in engineering practice, must be measured accurately by fluid measurement devices. Differential pressure flowmeters (e.g., the orifice plate, the Venturi and the V-Cone meter) are widely used in the measurement of gas and liquid flow rates in agricultural production (e.g., to measure the water discharge of inlets in agricultural irrigation systems [1,2]), the oil-gas industry (e.g., where wet flowmeters are used to measure gas flow in pipes [3]), scientific investigations and many other fields [4]. Flowmeters with conventional throttle elements constitute more than half of the instruments used in industrial flow measurement [5]. It is highly desirable that they have advantages such as a wide range of flow-rate measurement, insensitivity to the fluid performance, high immunity to external noise, low maintenance and low cost [6]. However, they in general have the disadvantages of inducing large eddies, being subject to high irrecoverable pressure loss, low measurement accuracy, a small turn-down ratio and the need for regular calibration [7]. For example, the orifice plate and nozzle can cause the flow to separate and form a vortex that can result in a relative pressure loss of more than 80%.

After the mid-1980s, the V-cone flowmeter [8], irregular Venturi flowmeter [9] and perforated orifice [10] were proposed to solve certain problems associated with conventional flow meters. Their flow fields are characterised by a circular-channel-adjusted fluid flow and the ability to maintain stable pressure in the channel flow, as well as having high precision, good repeatability and low pressure loss. A novel flow-measurement device comprising a long-throat Venturi tube and a V-cone was also proposed, along with a new metering method based on triple differential pressures. The correlations were based on the gas Froude number, gas–liquid density ratio and differential pressure ratios, which were then compared and validated in laboratory and field tests. The laboratory test results showed that the uncertainties of the relative errors pertaining to the gas and liquid flow rates were less than 3% and 6%, respectively [11]. Sapra et al. [12] studied the effect of the equivalent diameter ratio on the performance of the V-cone flowmeter. Liu et al. [13] considered cone flowmeters with different beta edges to have different applications and measurement performances. The authors reported that the sharp-angle beta edge performed best. Additionally, as the latest optimization of the standard orifice, the perforated orifice has a smaller critical Reynolds number and a stronger anti-disturbance ability. The constant discharge coefficient of the perforated orifice was reported to be 22.5–25.6% larger than that of the standard orifice in the experimental range [14].

With the development of computer technology, computational fluid dynamics (CFD) technology has been extensively used as an effective alternative to performing elaborate experiments [15]. Erdal and Anderson [16] used CFD to evaluate the performance of the V-cone flowmeter and showed that the predictions made by the standard k-ε turbulence model deviate significantly deviation from the experimental results. Singh and Seshadri [8] also used CFD to evaluate the performance of the V-cone flowmeter and establish the effect of swirl on its performance. In addition, this study has shown that the RNG turbulence model provides much better flow prediction, with the difference between the experimental and predicted results less than 4%. As such, researchers have begun to use these turbulence models to study the distribution of the internal flow field of the conical flowmeter and to optimize its parameters; others have proposed flowmeters with a specialised shape, such as the spindle flowmeter [17] and bipyramid flowmeter [18]. Singh et al. [8] used CFD to determine the effect of the annubar factor on the flowmeter body shape and concluded that there was only a slight pressure loss for an elliptical flowmeter with a high slenderness ratio. An optimized long-waisted bipyramid flowmeter was proposed based on the results of a flow field analysis [19]. The authors found that a constant-diameter-ring flow channel formed between the cone element and the pipe wall. The flow field of water through the cone element was studied via 3D CFD simulations, and the constant-diameter-ring channel was found to be able to adjust the flow of incoming fluid, and a small rear angle of the cone element could reduce flow separation and the overall pressure difference.

Other researchers have optimized the flow field effects of the conical flowmeter by changing relevant structural parameters, such as the equivalent diameter [12], radius of curvature, upstream swirl [8] and vertex angle [20]. Zhang et al. [21] used a double-cone flowmeter and performed a two-parameter measurement to compare the pressure drop associated with different conical bodies corresponding to the double cone in the pipeline. Borkar et al. [22,23] proposed the concept of a two-way cone flowmeter. Wei et al. [24] proposed a design in which the structural characteristics of the inner cone flowmeter were distorted. They used the pressure-receiving method, permanent pressure loss, outflow coefficient, rear cone angle, and other factors to optimize the cone shape. The results indicated that the optimal structure was achieved when both the front and rear cone angles were 20°. Ming Xiao et al. [17] proposed a new type of flowmeter, called the spindle flowmeter (SPF), which features good fluid mechanics. This flowmeter consists of a spindle-shaped throttle element and a long columnar part. The spindle-shaped throttle element can significantly reduce the flow resistance. The columnar component, which was inspired by the above double-cone flowmeter, guides the inlet flow into a uniform circular flow that provides stable pressure distribution and improves the accuracy and steady performance of the flowmeter [25]. Previous researchers have found CFD to be a significant design tool for instruments that measure flow after validation against experimental results, and have shown that this method can be exploited to consider the use of novel shapes for the throttle element. To improve the flow performance and measurement accuracy of the existing flowmeter, here we propose a novel differential pressure flowmeter (OSF) that uses a streamlined olive-shaped throttle element to form a standard ring flow channel in the ring passage. To achieve these aims, we compare the flow performances of the OSF and conventional OPF with respect to their streamlines, speeds and pressure distributions, and determine the pressure loss reduction of the OSF based on experiments and use of CFD. Experiments were conducted to compare the pressure losses at flow rates ranging from 7.54 to 17.91 m3/h of the proposed and the conventional OPF under the same conditions. Numerical simulations were also conducted using the RNG k-ε turbulence model, and the predicted results were validated against the experimental results. A numerical model was then applied to perform an extensive parameter analysis of the flow characteristics and relative pressure loss of the proposed OSF and the OPF at flow rates ranging from 0 to 50 m3/h. Our goal was to minimise the pressure loss and improve the overall energy of the conventional flowmeter, which will make a significant difference when widely applied in engineering practice.

Section snippets

Physical model of OSF

The size of the proposed OSF is characterised by having its maximum diameter (Dmax) at the location corresponding to the waist of the OSF. As shown in Fig. 1, the OSF with a diameter of 40 mm (40-mm OSF) is made of stainless steel and has three main parts: a measurement tube, a throttle element, and eight deflectors (with two quaternions distributed at the respective inlet and outlet of the throttle element). Although the complicated shape of the olive-shaped throttle element increases the

Experimental device

The pressure-loss test for the OSF was conducted at Jiangsu Yuanwang Instrument Co. Ltd., the experimental setup of which is shown in Fig. 2. Fig. 3 shows a schematic diagram of the experimental system, in which the oil pump transports diesel oil through the check valve, filter, pressure-regulating container and flow-regulating valve. It then enters the measurement pipe and returns to the fuel tank. The flow rate is controlled by the openness of the regulating valve. In the experiment, a

Details of numerical simulation

To gain insights into the flow mechanism, numerical simulations of the internal flows in the OSF and OPF were conducted using the commercial software ANSYS Fluent V14.5. To validate the performance of the numerical models, the pressure loss was measured experimentally and compared with the simulation results.

Experiment results and analyses

Experiments were conducted to verify the obtained simulation results. To perform the actual pressure loss test, a 40-mm diameter OSF prototype was designed.

Taking the centre point of the OSF as the origin point, Fig. 5 shows the distribution with axial static pressure. It can be seen that as the flow domain gradually shrinks, the static pressure of the fluid decreases rapidly (p1 point) and then increases rapidly after reaching the minimum value (p0 point). After returning to the maximum local

Discussion

Here we consider the differences between the OSF and SPF in detail to clarify the benefits of the OSF. In section 5.2.2, the streamline distributions of the OSF, OPF and SPF under the same conditions are compared, which reveal better flow performances of the OSF and OPF, with the occurrence of hardly any recirculation zones in their flow fields. The OSF was also found to provide more advantages, including bidirectional measurement and easy manufacturing.

As shown in Fig. 14, Fig. 15, we also

Conclusions

In this paper, a novel differential pressure flowmeter was proposed with an olive-shaped throttle element, and the flow characteristics of the OSF were analysed and compared with those of the OPF by numerical simulation and experiment. The main conclusions are as follows.

  • 1)

    The OSF has a good streamline shape with a relatively stable and uniform circular flow field around its cylindrical waist. The OSF also generates fewer vortexes after fluid passes through it. The pressure contours are evenly

CRediT authorship contribution statement

Guozeng Feng: Conceptualization, Methodology. Yuejiao Guo: Investigation, Data curation, Software. Dachuan Shi: Methodology, Writing - original draft, Supervision. Chen Gu: Visualization. Fengyuan Yu: Writing - review & editing. Tianhe Long: Writing - review & editing. Shaozhe Sun: Project administration.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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