Venturi Nozzle Ridges for Stable Air-Fuel Mixing
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Solution Overview
Problem
Conventional fan-suction mixing systems with venturi nozzles face challenges in maintaining a constant air-fuel mixing ratio due to fluctuations in combustion air flow rates, leading to changes in the flow coefficient and requiring a gas pressure adjusting mechanism.
Innovation Solution
A venturi nozzle with a narrowed nozzle portion and an enlarged mixing portion, featuring a plurality of grooves or ridges on its inner surface to suppress boundary layer separation and maintain a constant flow coefficient, along with a curved convex surface to reduce pressure loss and stabilize the mixing ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the output of the blower is changed to adjust combustion amount, then the flow rate of combustion air changes, but the flow coefficient of combustion air decreases due to boundary layer separation, causing the air ratio to become unstable
Solution Approach 1:
The inner surface of the nozzle portion is given a specific curved convex shape with particular geometric parameters (R1, R2, L1, L2, D1, D2) to create favorable flow conditions. This localized geometric modification suppresses boundary layer separation and maintains stable flow coefficient across varying combustion rates, resolving the contradiction between productivity adjustment and composition stability.
2Stability of the object's composition
If a gas pressure adjusting mechanism is added to maintain constant air ratio, then the mixing ratio stability improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The nozzle portion's curved convex surface geometry enables the venturi nozzle to automatically maintain stable flow characteristics and constant air ratio across varying combustion rates. The geometric design (R1, R2, L1, L2, D1, D2 parameters) allows the system to self-regulate without external pressure adjusting mechanisms, eliminating complex components while ensuring composition stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for a constant mixing ratio without a mechanical gas pressure regulating mechanism, reducing manufacturing costs and energy loss while maintaining stable combustion across varying combustion rates.
Implementation Method 1
fuel gas is drawn into the mixing portion from the fuel gas inlet by the venturi effect of combustion air drawn into the nozzle portion
Implementation Method 2
the influence of boundary layer separation on the surface of the venturi nozzle becomes large when the output of the blower is small
Data Source
AI summary
A venturi nozzle (1), disposed upstream from a blower (20), for mixing combustion air and fuel gas by intake pressure of the blower (20), comprising: a nozzle portion (12) with a shape that is narrowed in diameter downstream and into which combustion air is introduced; a mixing portion (13), disposed downstream from the nozzle portion (12), with a shape that is enlarged in diameter downstream and into which combustion air and fuel gas are mixed; and a fuel gas inlet (15), disposed between the nozzle portion (12) and the mixing portion (13), into which fuel gas is introduced; wherein a plurality of ridges (16) extending in a circumferential direction and arranged at predetermined intervals in a flow direction of combustion air are formed on an inner surface of the nozzle portion (12).