Market trends for equipment where cooling is required, are constantly becoming high-density and miniaturized in design. Such equipment requires quality fans with high static pressure capabilities, which are optimized to raise the cooling efficiency.
Criteria for a quality differentiation at fans:
- Motor Design (Slot Pole combination)
High efficient and Power saving
- Material selection:
Long life bearing
Used magnet material and plastic
- Efficient design method
Low acoustic noise
To realize the highest level of efficiency and performance with his fans, Nidec Servo selected a 3-phase type of Brushless as suitable motor, increasing immediate the efficiency with 10% versus a single phase motor. A further improvements was realized by increasing the diameter, making the motor more powerful.
By using SmFeN instead of Ferrite as magnet material, the magnetic flux increased with a factor of 1,4, and the higher hfe magnet of this material prevents demagnetization.
The fan blades are made of PPS as plastic material, preventing the deformation at high speed at high temperature.
For high static pressure applications, diagonal flow fans, (which exhaust in a centrifugal direction) or 2 axial fans mounted in series are usually considered. However, disadvantages may occur due to the direction of air-flow, physical size and cost.
Keeping up with these demands using traditional design methods, involves the time consuming approach of manufacturing and the testing of many trial samples.
New techniques, such as Computational Fluid Dynamics (CFD) have been introduced to assist in the design process. However, when using CFD, it is necessary to understand the complexities of axial fan design which have been refined over many years. Therefore, the important point is how CFD is mastered. In recognition of this fact, Nidec Servo has developed the Fan Optimization Design System, which combines all the strengths of CFD with an Optimization Technique to model a new design offering the desired characteristics.
By understanding the Pressure distribution lead to be the best design to reduce noise occurrence by the effectiveness of the blade shape. By numerical simulations, the used CFD analysis detected the large-scale of unsteady states of the Blade tip as leakage vortex breakdowns, as well as the mechanisms of aerodynamic noise generation in Fan for industrial or home use.
In addition, innovative design techniques for fan’s blades using CFD are applied to the design of rotor cascades for low-noise fans. The special shape of the fan blade, show not only a better result in a high airflow but also in a low noise level.
Now, Axial Fans can be rapidly designed to meet both high level performance requirements and specific application demands. Using this system, Nidec Servo has further developed their G-Series Axial Fan range.
Since one of the objectives of FODS is to allow easy use by the Designer the CFD function has been covertly incorporated into all levels of the design system.
As an integral part of the optimization process, CFD calculates the static pressure efficiency from the brake shaft power, static pressure and air-flow. The maximum calculated value of the static pressure efficiency is used to determine the optimized form required. Nidec Servo has combined CFD and the Optimization Technique to produce a fully automatic modeling tool which continually repeats this calculation loop selecting the next most suitable data range until the optimum form with highest static pressure efficiency is simulated.
There is a trade-off between the calculation time and accuracy. The higher number of lattices analyzed, the greater the accuracy, but longer calculation time is taken. The first important criteria is to balance the calculation time and accuracy so as to achieve the optimized result in the shortest time.
The general Procedure of CFD is as follows:
1. Model creation and form definition
2. Formation/creation of an analysis lattice (mesh)
3. Performance and physical para meter set-up
4 Analysis execution
The contours of an impeller and venturi are complicated 3-dimensional forms, which incorporate years of design knowledge. To utilize the Optimization Technique, these 3-dimensional forms are translated into numerical parameters.
Using the performance data and dimensional analysis of conventional fans and then translating this information into numerical parameters, Nidec Servo has been able to construct a comprehensive data file. This allows a total of 23 individual parameters, which are key factors in the fan performance, to be addressed during the design process
- Creation of the Analysis Lattice: The inputs of 23 individual numerical parameters, derived from the form definition creates a direct analysis lattice. The number of lattices, their size and surface finish can be adjusted if required. The creation of a lattice for a single impeller takes less than 60 seconds.
- Fluid Analysis; Using CFD software, analysis of the required parameters is carried out. During analysis, the system rewrites the macrocode automatically from the specified design points, e.g. required air-flow, static pressure, etc. The results are stored as part of the Optimization Technique for future use.
- Optimization; The Simulated Annealing (SA) method has been adopted for the optimization technique. Combined with Nidec Servo”s broad knowledge of applications, highly reliable and accurate analysis can now be rapidly conducted.
By using the FODS, Nidec Servo has developed new version of axial fans, which offers high static pressure performance and more airflow without compromising in size and noise level.
These cUL/TUV approved High performance ball-bearing fans are very suitable for use Industrial and IT market. The new models come in various popular frame sizes from 80x80x38mm; 92x92x38mm; 120x120x38mm, and 134x134x38mm, and in different DC-voltage.
The housing of the fan is available in plastic or aluminum.
The fans also have a brake system, securing that the rotor will stop within 2 sec., when the motor power is disconnected (for maintenances or safety purposes)
The DC fans and blowers of Nidec Servo can also have functions that send an alarm signal when the fan motor revolutions slow down (lock detection, pulse output, speed detection). These fans offer standard a PWM speed control and speed sensor. The variable speed operation is possible by means of a PWM input signal, resulting in further reduction of the power consumption and noise, as requested during idling.
Dynetics will be present on the PCIM 16 – 18 May in Nuremberg, Germany at stand nr. 144 – 9 showing these new fan models as enhancement to our wide range of fans and blowers.