Controllable Pitch Propellers

Tailor-made CP-propellers for optimum efficiency

Sustainable propulsion from tailor-made blade design for optimum propeller efficiency with low vibration and noise levels

Sustainable Propulsion

Brunvoll aim to be a strong contributor to a sustainable shipping industry by providing systems designed for efficient operation.  
  • We offer propeller systems designed in compliance with the highest industrial standards such as US EPA VGP2013, DNV Clean, DNV Clean Design requirements.
  • We are reducing risk of marine pollution by using Computational Fluid Dynamics (CFD) methods for efficient full-scale propeller design and testing.
  • Our design principles for optimum efficiency, minimum cavitation and lowest possible noise and vibration levels, gives less stress on marine resources.

Brunvoll CP-Propellers product range

  • Four-bladed propellers
  • Hub diameter from 520 - 1950 mm
  • Propeller diameter from approx 1600 - 9000 mm
  • Power range from 500 - 20.000 kW
  • CP-propellers with pitch mechanism either in the gearbox, in the shaft line or in the propeller hub
  • Blade design of high skew or normal skew
  • Propeller and hub material NiAl Bronze or stainless steel

Optimised Propeller Systems

Brunvoll serves a large variety of vessel applications. There is a continious demand for propeller designs to be optimised in order to achieve the highest energy efficiency. All Brunvoll CP- and FP-propeller configurations are designed for the individual ship.

Design principles of Brunvoll CP-Propellers

  • Propeller designs are optimised to the individual ship.
  • All designs are based on established hydrodynamical theories and tank test results.
  • Propeller blade data, such as diameter, pitch, rpm, skew and load distribution are always carefully selected to give the best solution with respect to both efficiency and noise/vibration characteristics.
  • Propeller blades are machined, polished and statically balanced according to ISO tolerances.
  • Our propellers can be supplied with certificates from any major classification society, and to the strongest arctic ice class requirements.
  • Interchangeable blade bearings.

Increase propulsion efficiency by applying the optimum nozzle profile

A ducted propeller gives up to 30% higher thrust at low speed compared to an open propeller.
  • Brunvoll HE nozzle profile is recommended for ships with high bollard pull requirements and low propeller load at higher vessel speed.
  • The 19A nozzle profile is recommended for many ships due to its good overall performance in different operating conditions.
  • The 37 nozzle profile is recommended for ships with high priority to equal performance in both flow directions, typically DP and astern operation.
  • Brunvoll is optimising the propulsion efficiency by applying the most suitable nozzle profile for the given service profile.

Feathering Propeller

Feathering is an option on standard CP-propeller systems. On a feathering propeller the blade angle can be arranged in line with the water flow.

This reduces the water resistance and gives the following advantages;

  • power reduction by shutting down one of the two propellers in twin screw systems
  • allows for maintenance at sea of one shaft line while the other is in operation

With twin screw installation and one side out of operation it is possible to reduce requirements for the shaft brake with CP-propeller.

The advantages of a CP-Propeller

  • The blade angle of CP-propellers varies from full ahead to full astern pitch.
  • A CP-propeller offers a higher maximum bollard pull, as it is possible to optimise the relation between rpm, pitch and power.
  • With variations in operating conditions, propeller performance is enhanced with a CP-propeller due to optimum pitch/advanced ratio.
  • A CP-propeller increases flexibility if available engine power is reduced.
  • For nozzle propellers the propeller blades are replaceable inside the nozzle
  • The propeller blade bearings are made of high performance self-lubricating and wear resistant material, which increases the lifetime of the propellers.

Brunvoll CP-Propeller System

  • A push-pull rod from the pitch mechanism in the hub through the propeller shaft to the servo motor piston located either in the gearbox or in the shaft line.
  • Push-pull rod systems are often used because of their simplicity and easy accessibility for maintenance inside the vessel.
Brunvoll CP Propeller system with push-pull rod and servo system in gearbox

Brunvoll ECP-Propeller System

Brunvoll ECP propeller hub mechanism
  • Servo piston located in the propeller hub.
  • The low pressure oil system is controlled from the oil distribution system in the gearbox or from a separate OD-box.
  • The hub servo system is recommended where the length of propeller shafts exceed 20 meters or in cases with highly loaded propellers with large servo forces in combination with moderate or long shafts.
Brunvoll ECP Propeller system with hub servo

Starter characteristics

Direct On-Line starter

Starting current:

5-10x Nominal motor current (IN)

Pros:

Low price and high starting torque

Cons:

High in-rush current

Description:

The Direct On-Line (DOL) starter consists of a contactor and a protection device such as a circuit breaker. The contactor is energized when the start button is pressed, and the full line voltage is connected to the motor. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Star-Delta starter

Starting current:

2-3x Nominal motor current (IN)

Pros:

In-rush current reduced with approx. 60% compared with DOL

Cons:

Reduced starting torque

Description:

The star-delta starter method applies reduced voltage to the motor, thus reducing current, during startup. This method requires that both ends of motor winding terminals are available. When connected in star each winding has less voltage (1 / √3 ~ 60%), and thus will have reduced starting current and torque. When full speed is reached the motor is connected in delta, having full torque available. Propeller pitch can be increased, and load applied when motor is connected in delta. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Auto-Transformer

Starting current:

2-3x Nominal motor current (IN)

Pros:

In-rush current reduced with approx. 60% compared with DOL

Cons:

Reduced starting torque

Description:

Auto-Transformer also applies reduced voltage in steps to the motor during startup. The transformer voltage ratio can be designed to the application, typically having a 50-70% motor voltage during startup. The motor consumes less current at a lower starting voltage. For example, with a 50% tap on the Auto-Transformer, the motor draws half its rated current, or about 25% of what it would draw with a DOL starter. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Electronic soft starter

Starting current:

2-2,5x Nominal motor current (IN)

Pros:

In-rush current reduced 

Cons:

Reduced starting torque.
Based on electronics

Description:

An electronic soft starter is a starting device that controls the way electricity is provided to the motor by using active switching devices such as thyristors. The device works in both in-line and in-delta configuration modes in three-phase motors. 

This starting method is ramping up the motor voltage in the starting sequence resulting in a reduced start-up current, allowing for a smooth and surge-free increase in motor torque. The voltage dips, stress, and wear and tear on the mechanical parts are all reduced as a result. Due to the thyristors there will be harmonic distortion of the current, and the influence on system voltage will depend on starting current and system impedance. Motor is started with propeller in zero pitch position (IZP).

Click the images to enlarge

Frequency converter starter

Starting current:

0,5x Nominal motor current (IN)

Pros:

In-rush current reduced.
Full speed and torque control

Cons:

THD generated, filters required.
Based on electronics

Description:

This is an electronic-controlled approach for starting asynchronous motors smoothly. It controls the frequency and current for the motor with electronics inverter circuits, avoiding large startup current. The thruster system's mechanical parts will be protected from high load because of the smooth start-up, and the this will also reduce the load on generators during startup compared to line-starter options. Depending on required performance torque and current may be below nominal values during startup. This is the high-end solution for the starting the thrusters, giving benefits such as smooth start, better energy economy, reduced wear and tear and process optimization.  Other benefits include motor speed stability during load changes and a longer motor life overall. Motor is started with propeller in zero pitch position (IZP).

Frequency converter starters may have different interface towards the main switchboard where 6-pulse rectifier is the most common, but both 12/24 pulse and Active Frontend (AFE) are used.6-pulse starters are the most common type, widely used due to the compact design and availability.The disadvantage with the 6-pulse starter is the increased THD during startup, particularly in smaller power system with large thrusters this might be an issue. 

To mitigate the THD a 12 or 24 pulse transformer and rectifier may be chosen, typically used for larger thrusters in larger ships. 
Frequency converter starters with active front end guarantees sinusoidal current and does not require a transformer. The AFE rectifier and LCL filter is more spacious than the 6-pulse rectifier and is suitable for high end solutions and ships with relatively small power system compared to thruster power.

Click the images to enlarge

A typical scope for a Brunvoll Propeller System consists of:

  • Propeller hub and blades
  • Stern tube and stern tube seals
  • Propeller shaft
  • Shaft couplings
  • Propeller nozzle
  • Control system
  • Temperature sensors, earthing device etc.

PROPELLER

BRUNVOLL CP PROPELLER RANGE
HUB SIZE 520 - 1 950 mm
PROPELLER DIAMETER 2 000 - 9 000 mm
POWER RANGE 1 000 - 20 000 kW

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Per Endre Woldsund

Per Endre Woldsund

Sales Manager, Brunvoll Volda AS

+47 905 72 814
per.woldsund@brunvoll.no
Vidar Liaskar

Vidar Liaskar

VP Sales, Brunvoll Volda AS

+47 952 57 129
vidar.liaskar@brunvoll.no
Arnfinn Brautaset

Arnfinn Brautaset

Sales Manager, Brunvoll Volda AS

+47 915 77 678
arnfinn.brautaset@brunvoll.no
Kirsti Gjørvad

Kirsti Gjørvad

Senior Sales Manager, Brunvoll Volda AS

+47 916 29 430
kirsti.gjorvad@brunvoll.no
Stig Helland

Stig Helland

Sales Manager, Brunvoll Volda AS

+47 911 11 595
stig.helland@brunvoll.no

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