Mixed Flow Pump Impeller

The Mixed Flow Pump Impeller is the core working component of a mixed-flow pump (also known as a slanted-flow pump). Its uniqueness lies in the fact that the direction of the liquid exiting the blades is between that of a centrifugal pump (pure radial) and an axial-flow pump (pure axial) - the liquid gains both centrifugal force and axial thrust, hence it is called "mixed flow".
This mixed outflow method enables it to have the dual advantages of large flow rate (close to that of an axial-flow pump) and medium head (higher than that of an axial-flow pump and lower than that of a centrifugal pump) when operating in the medium to high speed ratio range of ns = 300–600. The hydraulic efficiency can reach 82%–92%.
Its typical structure consists of twisted blades in space + cylindrical or spherical hubs: The blades undergo three-dimensional space twisting from the inlet to the outlet (twist angle 20°–60°) to adapt to the gradual turning of the liquid flow from radial to axial; the number of blades is usually 3–6 (a few-blade design reduces the risk of blockage and improves cavitation performance); the hub ratio is 0.3–0.6, and it can be either closed (with front and rear cover plates) or semi-open (only the rear cover plate).
As the most critical component of a mixed-flow pump, the hydraulic profile of it directly determines the efficiency, cavitation margin, flow-head curve shape and operational stability of the entire pump.

Space-distorted blades: The blades undergo three-dimensional spatial distortion from the inlet edge to the outlet edge (twisting angle 20°–60°). The profile has been optimized through CFD hydrodynamic simulation and model testing, enabling the liquid flow to smoothly transition from radial to axial, reducing secondary flow losses, and achieving a hydraulic efficiency of 82%–92%.
Fewer blades design: The number of blades is typically 3–6 (commonly 4–5), which is less than the 6–8 blades in centrifugal pumps, reducing the risk of blockage, improving cavitation performance, and reducing weight.
Hub structure: Cylindrical or spherical hubs, with a hub ratio of 0.3–0.6; spherical hubs can further optimize the inlet flow pattern and reduce NPSHr to 2–4m.
Closed/semi-open type: Closed impellers have front and rear covers, high efficiency, small axial force, suitable for clear water and mild sewage; semi-open impellers only have a rear cover, with a spacious flow channel and resistance to blockage, suitable for conditions with a small amount of particles.
Adjustable blade mechanism (large impellers): For Mixed Flow Pumps with a diameter of ≥500mm, an adjustable blade structure can be configured. The blade inclination angle can be adjusted through hydraulic or mechanical mechanisms (±8°–±12°) to achieve a shift in the performance curve.

Operating conditions parameters: Flow rate Q × Head H (including geometric height difference + pipeline loss), determine the specific speed ns to fall within the 300–600 mixed flow range
Medium characteristics: Clear water / Mild sewage / Sandy muddy water / Seawater / Corrosive liquid → Determine the material route
Adjustment requirements: Whether the operating conditions fluctuate greatly → Decide whether to select adjustable blade structure
Installation method: Horizontal (HW volute type) vs Vertical (mixed-flow pump) vs Guide vane type (vertical mixed-flow)
Cavitation condition: The device's cavitation allowance NPSHa matches the impeller's NPSHr (requires NPSHa > NPSHr + 0.5m safety margin)
Efficiency requirement: For large pumping stations, every 1% increase in efficiency results in considerable annual energy savings. Prioritize CFD optimization of the hydraulic model
Custom service: Processing based on drawings and samples, OEM brand marking, special material casting (duplex steel/bronze/high-chromium alloy/composite material), adjustable blade structure design, customized CFD hydraulic optimization design, precision casting + CNC machining, dynamic balance verification (G6.3/G2.5 grade), static balance/dynamic balance report, complete set of parts for the impeller + hub + blade, repair and remanufacturing of old impellers (stacking welding/spraying/laser cladding).

Series Selection Guide:
HW Type Volute Impeller - Simple structure, low cost, flow rate 100–2000 m³/h, head 3–12 m, preferred for farmland irrigation
QSH/QSL Vertical Axial Flow Impeller - Vertical installation, stable operation, flow rate 2000–15000 m³/h, head 5–18 m, main for power plant circulating water / municipal stormwater pumping stations
HL Type Guide Vaned Mixed Flow Impeller - Large vertical type, flow rate 15000–30000 m³/h, head 8–25 m, diversion and regulation / water conservancy hub
Adjustable Blade HL Type - Extra-large size, flow rate 30000–50000 m³/h, head 10–25 m, adjustable blade inclination angle ±8°–±12°, large-scale pump stations with fluctuating conditions
Material System:
HT200 Gray Cast Iron - Standard clear water conditions, highest cost-performance ratio
QT500-7 Spheroidal Cast Iron - Slightly abrasive or requires higher strength
304/316 Stainless Steel - Mild corrosion medium (pH 4–10)
Duplex Steel 2205 - Chloride ion conditions (seawater, salt lakes)
Bronze ZCuSn10Pb1 - Seawater, ships, resistant to marine organism adhesion
High Chromium Alloy Cr26 - Turbid water conditions with sand abrasion
Duplex Steel + Copper Alloy Composite - Special anti-corrosion and wear resistance requirements

CZME is a world-class manufacturer of high-performance pumping solutions, serving industries such as mining, construction, environmental protection, and water treatment. We specialize in the production of Slurry pumps, Dredge pumps, Desulfurization pump, Marine dredging pumps, and other industrial pumps designed for handling solid-laden, highly abrasive, and corrosive slurries. Our expertise in slurry and wastewater management makes us a trusted partner for clients worldwide.

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