Parametric Study on the Thrust of Bubbly Water Ramjet with a Converging-Diverging Nozzle

Fu, Yingjie; Wei, Yujia; Zhang, Jiazhong

doi:10.1016/s1001-6058(08)60189-4

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…However, if we define a converging–diverging nozzle shape with high vessel velocity, either the bubblly flow will choke before the minimum area and the flow rate will decrease, or the flow will not choke, but will diffuse in the diverging section of the nozzle. 26 In this study, the velocity profile of the water phase is specified by…”

Section: Solution Techniquementioning

confidence: 99%

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

Zhang

Xia

Huang

et al. 2018

Proceedings of the IMechE

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To predict engine performance and further instruct the integral engine design, a more reasonable and accurate numerical model of the two-phase underwater ramjet was introduced in this article by considering the bubble formation process. Two-fluid model was used to examine the bubbly flow in the nozzle and its mathematical model was solved by a fourth-order Runge–Kutta method. Subsequently, the influences of vessel velocity, gas mass flow rate, navigational depth, and orifice diameter of the bubble injector on the performance of the engine were discussed. Results show that, compared with convergent nozzle, Laval nozzle is proved to improve the thrust of the engine, especially at relatively high velocity and gas mass flow rate. With the other conditions fixed, there is an optimum vessel velocity for the ramjet, in which maximum thrust is generated. And a smaller orifice diameter always promotes the engine performance, while this promotion is negligible when the orifice diameter is smaller than 1 mm. Besides, increasing backpressure will cause serious performance drop, which means that the the two-phase underwater ramjet is only efficient for shallow depths.

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Section: Solution Techniquementioning

confidence: 99%

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

Zhang

Xia

Huang

et al. 2018

Proceedings of the IMechE

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“…That research can serve as a convenient tool for determining the operating parameters of practical vehicles. More work on air-augmented waterjet has been conducted in the last two decades, e.g., Dynaflow's research [17][18][19], Gowing et al [20], Fu et al [21], Liu et al [22], and Zhang et al [23]. They included certain analytical aspects, numerical calculations, and experiments, typically in static systems with transparent walls allowing visualization of the flow development and phenomena.…”

Section: Introductionmentioning

confidence: 99%

Open-Sea Testing of Two-Phase Marine Ramjet Propulsion

Valensi,

Gany

2023

JMSE

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Open-sea testing of a two-phase marine ramjet vehicle has been conducted. This experimental phase was accomplished following comprehensive theoretical research. The concept of two-phase marine ramjet propulsion consists of a submerged propulsor acquiring water through an inlet due to the vehicle’s motion. Thrust is generated by injecting and dispersing air (or gas) bubbles within the water flowing through the propulsion unit channel and expelling a jet of the two-phase flow through an exit nozzle. The bubbles injected into the internal flow transmit their expansion work to the outgoing jet, resulting in an increase in the jet velocity, hence generating thrust. The article briefly describes the thrust generation concept, then it presents the overall system and thrust units attached to the test vessel, and finally, it summarizes the open-sea experimental results. Good correspondence between the theoretical prediction and actual test data is shown, revealing the feasibility of the two-phase ramjet concept at the low to intermediate cruise velocity range and a smaller relative thrust margin over the hydrodynamic resistance at the high-speed range.

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“…Gowing et al [8] applied a similar model to simulate a steady one-dimensional bubbly flow in three different convergent nozzles; their predicted thrust and efficiency were nearly identical to the experimental results. Fu et al [26] analyzed bubbly flow in convergent-divergent nozzles using a two fluid model and discussed the influence of mass flow rate, nozzle area ratio and bubble radius on the jet thrust. Wu et al [9] developed a trajectory model for bubbly flow in which the drag, virtual mass, pressure gradient, gravity and Saffman forces for bubbles are taken into account.…”

Section: Introductionmentioning

confidence: 99%

Interphase Mechanical Energy Transfer of Gas-Liquid Flow in Variable Cross-Section Tubes

Feng

Yang

Li-zi

et al. 2023

JMSE

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The use of gas energy includes a wide range of applications to directly accelerate the liquid in a pipeline without the aid of mechanical equipment, such as marine gas-liquid jet propulsion. To clarify the characteristics of energy transfer by interphase forces for gas-liquid flows in variable cross-section tubes, two-fluid models of annular flow, bubbly flow and homogeneous flow were adopted, respectively, along with four newly elaborated coefficients, which are the work factor of gas fg, reflecting the relative ability of gas to power liquid, the interface work transfer coefficient kg (representing the relative magnitude of mechanical work received by liquid from gas), the interphase work-to-energy conversion coefficient kl (denoting the capability of energy transfer through work performed by interphase forces) and the interphase mechanical efficiency ηw. The results reveal the interphase work transfer is strongly influenced by the structural parameters of the tubes (or nozzles), and an optimized design is necessary to improve the performance. The higher the degree of gas dispersion in the liquid, the more advantageous the conversion of gas work into the liquid’s mechanical energy. Of these three flow patterns, annular flow has the lowest kl and ηw (kl = 0.0797, ηw = 0.9885 in present example), while homogeneous flow displays the limit of interphase mechanical energy conversion because the gas-liquid momentum coupling reaches the maximum (kl = 0.9979, ηw = 1).

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Parametric Study on the Thrust of Bubbly Water Ramjet with a Converging-Diverging Nozzle

Cited by 8 publications

References 13 publications

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

Open-Sea Testing of Two-Phase Marine Ramjet Propulsion

Interphase Mechanical Energy Transfer of Gas-Liquid Flow in Variable Cross-Section Tubes

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