Optimization on Fan Efficiency
and the Number of Blades
This data can be used to analyze the dependence of fan efficiency
on the proposed cross-sectional area of a new shaft.
The implementation of a crossflow fan in a wing was first proposed by Nikolaus Laing in 1964 , who together with Bruno Eck are responsible for increasing the crossflow fan efficiency
. Hancock  worked on raising the efficiency of the crossflow fan implementation at Lockheed up to the value of 82%.
A single-duct VAV system using either all series or all parallel FPTUs was defined in EnergyPlus using the Energy-Plus Objects "HVACTemplate:Zone:VAV:FanPowered" and "HVACTemplate:System:VAV" with a series of temperature, pressure, fan efficiency
, and airflow inputs shown in Table 4.
The defaults in the template include values of 70% for the terminal unit fan efficiency
, 1,000 Pa (4 in.
in the designed operating point not less than 82%.
* The MMIL-XTM delivers tip to 42% efficiency, an increase over a typical tubeaxial fan efficiency
requirements appear for the first time.
Changing the size or shape of fans can help to optimise fan efficiency
and airflow, thereby reducing energy consumption.
The scientists found that none of the devices performed well in all of the key functions: fan efficiency
, efficiency in capturing polluted air for exhaust and sound levels.
Figures 3a and 3b show pressure, efficiency, and power curves for two different fan types to illustrate how the shape of fan efficiency
curves affects the fan power draw.
Tom Pelland, director of the next-generation product family at P&W, says: "Engine manufacturers have always had to make some trade-off between fan efficiency
and LPT/LPC efficiency.