Carurettor Venturi Types

What Is A Carburettor Venturi? It’s Types & Working Principle


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What is a Carburettor Venturi?

Carburettor venturi is a ’tube or passage’ that decreases considerably. It is narrower at the center and thru’ which the air must pass. As the same amount of air must pass thru’ this tube, its velocity or speed is greatest at the narrowest point of the tube. If you reduce this area, even more, the velocity of the air increases. As a result, it proportionately increases the suction of fuel.

The opening of the fuel discharge jet is typically located where the suction is greatest. It is, generally, just below the narrowest section of the venturi tube. The vaporized gasoline sprayed thru’ the fuel jet mixes with the air entering thru’ the carburetor venturi tube in the mixing chamber located below the discharge jet. This produces a combustible mixture that passes thru’ the inlet manifold into the engine cylinders.



Carburettor Venturi and vaporization:

While the carburettor atomizes most of the fuel in the mixing chamber, it vaporizes only a small part of the fuel. The amount of fuel vaporized depends upon the nature of the fuel, the temperature of the air, fuel and engine parts, the amount of suction created above the fuel jet and the degree to which the fuel is broken up or atomized. The process of vaporization of the air-fuel mixture is usually NOT complete until the end of the compression stroke. The system continues to vaporize the fuel right until the end of the compression stroke of the petrol engine.

Types of Carburettor Venturies: How Venturi type affects the carburettor’s performance

There are many types of carburettor venturies depending upon their application. The carburettor designs vary according to the type and the number of venturies they employ. Besides, each of these designs provides decreased pressure which draws more fuel from the discharge jet. This creates a vacuum or negative pressure which helps in vaporization. Multiple carburettor venturies help in keeping the fuel away from the carburettor walls which reduces condensation.



Following are the types of venturies employed in a carburettor:

1. Plain or Single Carburettor Venturi-

This type of carburettor venturi is known as ‘Plain or Single’ venturi. It employs only the Single venturi which acts as the main venturi thru’ which the air passes to the engine intake manifold.

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