Question

The volumetric efficiency of naturally aspirated engines ranges between
1. 20-30 % 
2. 75-85 % 
3. 50-60% 
4. 95-100 %

Answer 1

Correct Answer - Option 2 : 75-85 % 

Explanation:

Naturally aspirated engines:

• Naturally aspirated engines where atmospheric air is inducted.
• If the pressure during the intake stroke is less than the pressure during the exhaust stroke, this is the situation with naturally aspirated engines.
• Typical maximum values of volumetric efficiency for naturally aspirated engines are in the range of 75 to 85 percent.
• In naturally aspirated engines break mean effective pressure (BMEP) does not stress limited, It then reflects the product of volumetric efficiency (ability to induct air), fuel-air ratio (effectiveness of air utilization in combustion), and fuel conversion efficiency.
• The maximum brake means effective pressure for turbocharged and supercharged engines is higher than for naturally aspirated engines.
• In diesel, the residual fraction is smaller (a few percent) due to the higher compression ratio, and in naturally aspirated engines is approximately constant since the intake is unthrottled.

• Turbocharged engines where the inlet air is compressed by an exhaust-driven turbine compressor combination.
• Supercharged engines where the air is compressed by a mechanically driven pump or blower are common.