The Pipe Diffuser: An Efficiency Enhancer in Centrifugal Compressors

      In modern industry, the centrifugal compressor increases the gas pressure as a key fluid machinery. The diffuser plays a crucial role among the many components of a centrifugal compressor. In particular, with its unique design and high efficiency, the pipe diffuser is essential in centrifugal compressors with high-pressure ratios.

     The pipe diffuser is a unique diffuser designed for use in centrifugal compressors. It guides the airflow through a series of tubular structures, converting the kinetic energy of the high-speed airflow at the impeller exit into pressure energy. Compared to traditional vane-less diffusers, the pipe diffuser is more effective in controlling the flow direction of the airflow, reducing flow losses along the path, and thereby improving the compressor's operational efficiency.

Figure 1: Schematic Diagram of the Tube Diffuser

 

Key Design Points of Pipe Diffusers

1. Geometric Parameter Optimization: The design of the pipe diffuser involves multiple geometric parameters, such as throat diameter, outlet diameter, and diffuser length. Optimizing these parameters is crucial for enhancing the diffuser's performance.
2. Flow Matching: To ensure the airflow entering the diffuser has the appropriate flow characteristics, the design of the pipe diffuser needs to be closely matched with the impeller's exit characteristics. This helps to minimize flow losses.
3. Internal Flow Control: The pipe diffuser can effectively control the direction and velocity distribution of the airflow through careful design of the internal structure, reducing flow separation and vortex formation. This improves the efficiency of pressure conversion in the gas.

 

Performance Advantages of the Pipe Diffuser

1. High Efficiency: The pipe diffuser can maintain a high adiabatic efficiency across a wide range of flow rates due to its ability to effectively control airflow.
2. Wide Flow Range: The pipe diffuser's optimized design accommodates various operating conditions and offers a broad flow range.
3. Compact Structure: Tube diffusers generally have a smaller size and weight, making them particularly advantageous in applications with limited space.

 

TurboTides in Pipe Diffuser Design

The TurboTides geometric module supports parametric modeling of pipe diffusers, allowing users to customize various parameters of the pipe diffuser, including the inner tube length, diffuser divergence angle, diffuser outer diameter, throat diameter, and the radial angle, as shown in the figure below.

 

Figure 2: Parametric Definition of Pipe Diffuser

 

The parametrically generated tubular diffuser and its flow path information are shown in the figure below.

 

Figure 3: Parametric Centrifugal Compressor with Pipe Diffuser in TurboTides

 

After completing the parameterization, TurboTides supports switching to the CFD module to automatically generate meshes with a single click and import boundary conditions, as shown in the figure below.

Figure 4: Mesh Generation for Compressor with Pipe Diffuser

 

 

After the mesh is generated, CFD simulation and analysis can be conveniently performed. The CFD simulation results for a centrifugal compressor with a pipe diffuser are shown in the figure below.

Figure 5: CFD Simulation Results for a Centrifugal Compressor with a Pipe Diffuser in TurboTides

 

Conclusion

The pipe diffuser represents a significant innovation in centrifugal compressor design. By optimizing the process of converting airflow kinetic energy, it can significantly enhance compressor efficiency and performance. With the advancement of Computational Fluid Dynamics (CFD) and numerical simulation technologies, the design and optimization of pipe diffusers will become more precise, leading to broader applications across various fields.

TurboTides' support for modeling and analyzing pipe diffusers makes their development more efficient and streamlined. The parametric modeling functionality allows simple, flexible, and easily adjustable diffuser designs. Combined with the seamlessly integrated CFD simulation module, performance simulation becomes more accurate and convenient.

In the future, TurboTides will continue to support the development of pipe diffusers, which will contribute to improved energy utilization efficiency and drive industrial progress.