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This study aims to investigate the noise-inducing characteristics during the start-up process of a mixed-flow pump and the impact of different start-up schemes on pump noise.

This study conducted numerical simulations on the mixed-flow pump under different start-up schemes and investigated the flow characteristics and noise distribution under these schemes.

The results reveal that the dipole noise is mainly caused by pressure fluctuations, while the quadrupole noise is mainly generated by the generation, development and breakdown of vortices. Additionally, the noise evolution characteristics during the start-up process of the mixed-flow pump can be divided into the initial stage, stable growth stage, impulse stage and stable operation stage.

The findings of this study can provide a theoretical basis for the selection of start-up schemes for mixed-flow pumps, reducing flow noise and improving the operational stability of mixed-flow pumps.

For underwater hydraulic machinery, the unique structure significantly enhances the three-dimensional non-uniformity of turbulence within the flow domain and high Reynolds number turbulence introduces complex effects on the machinery. Therefore, studying the turbulent flow characteristics in underwater hydraulic machinery is crucial for system stability.

This paper conducts a numerical analysis on a specific type of underwater hydraulic machinery. A numerical calculation model is established under stable inflow conditions to analyze the flow trends and pressure changes at different flow speeds. Subsequently, structural modifications are made to the underwater hydraulic machinery, and the characteristics of the velocity field, pressure field and vorticity distribution under different model parameters are analyzed.

The results indicate that changes in internal structure have a certain impact on flow characteristics. When the structural changes are significant, the fluid flow becomes more complex and pressure fluctuations become more intense. The research findings provide a scientific basis and theoretical guidance for the structural design of underwater hydraulic machinery and have significant research implications for controlling fluid-induced noise.

Affected by the inherent structural characteristics of the flow channel structure, the flow direction of the high-speed water flow changes drastically in the flow channel, so it is of great significance to study its flow characteristics for the stability of the system.

This study aims to analyze a novel phenomenon observed in recent years regarding the internationalization strategies of Chinese mobile internet e-commerce platform companies, which could extend traditional internationalization theories based on the experiences of companies from developed countries and traditional Chinese industries.

The traditional Uppsala model and imitation learning model of firm internationalization theory do not fully explain the motivations and behaviors behind new market entry in the internationalization practices of Chinese mobile internet companies. This study begins with the new internationalization practices of Pinduoduo, the fastest-growing mobile e-commerce platform in China, with the growth desperation theory as a perspective. By drawing on grounded theory methods, it explores the motivations and entry modes of internationalization within the broader context of recent Chinese mobile internet companies expanding abroad. This provides a theoretical explanation for traditional internationalization motivation and entry mode theories based on the new phenomenon of Chinese mobile internet platforms. Additionally, using Stata software and event study methodology, the financial performance and stock market performance of Pinduoduo’s new market entry behavior are analyzed.

It posits that when enterprises face pressures related to domestic market growth constraints, they tend to adopt strategic decisions for new market entry to alleviate growth pressures based on new growth opportunities and platforms. During the process of entering new markets, enterprises tend to adopt the “Copy from China” (CFC) model to efficiently replicate the successful experiences in the Chinese market. Market selection for new entries is determined based on psychological distance.

First, the case study provides valuable insights for other mobile internet platforms, but these insights may not be directly transferable to companies in traditional industries; second, directly replicating well-developed business operations and marketing models from the Chinese market to new global markets might face cultural adaptability issues. How could firms balance the general principles of the Chinese internet model with the unique contexts of different global markets will be a crucial focus for future research.

Pinduoduo’s new market entry strategy represents a microcosm of Chinese mobile internet e-commerce platform enterprises’ international expansion choices, reflecting a significant phenomenon and future trend in Chinese business practices. Against the backdrop of widespread growth bottlenecks in current Chinese mobile internet e-commerce platform companies, adopting the CFC model to explore overseas markets in the future presents an opportunity for companies to expand new growth platforms, offering insights for current business practices.

This paper attempts to construct a new theoretical explanation for internationalization with unique characteristics of the Chinese mobile internet industry, based on the integration of “internationalization theories – internationalization practice – comprehensive research methods.” The study enriches strategic literature on the factors influencing new market entry for Chinese mobile internet e-commerce platform companies by exploring how increased growth pressures affect their strategic decisions to enter new markets. Meanwhile, it reveals a new market-entry-mode, the CFC (Copy from China) model, which reflects current trends in the practices of Chinese mobile internet e-commerce platform companies, providing practical insights for the international expansion activities of mobile internet companies in other industries.