Question
Download Solution PDFWhich scavenging method in two-stroke engines has the disadvantage of poor scavenging at full throttle and has the necessity of water cooling?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFExplanation:
Cross Scavenging in Two-Stroke Engines
- Cross scavenging is a method used in two-stroke engines to remove the burnt exhaust gases from the cylinder and replace them with a fresh air-fuel mixture.
- In this method, the incoming air-fuel mixture enters the cylinder from one side and pushes the exhaust gases out from the opposite side, typically through ports located near the top of the cylinder.
- In a cross-scavenged two-stroke engine, the fresh charge enters the cylinder from the intake port, which is located on one side of the cylinder wall.
- As the piston moves downwards during the power stroke, it uncovers the exhaust port on the opposite side, allowing the burnt gases to escape.
- The incoming fresh charge then pushes the remaining exhaust gases out through the exhaust port, completing the scavenging process.
Advantages:
- Simplicity in design and construction, making it easier to manufacture.
- Suitable for small and medium-sized engines where space constraints are important.
Disadvantages:
- Poor scavenging efficiency at full throttle, leading to incomplete removal of exhaust gases and reduced engine performance.
- Necessity of water cooling to manage the heat generated due to the inefficient scavenging process.
- Potential for fresh charge to escape through the exhaust port before complete scavenging, resulting in fuel wastage and higher emissions.
Applications: Cross scavenging is commonly used in smaller two-stroke engines, such as those found in motorcycles, small boats, and handheld power tools, where simplicity and cost are critical factors.
Last updated on Jul 9, 2025
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