Inner Flow Field And Noise Characteristcs Research Of Integrated Stove Duct

The integrated stove first appeared in China in 2003.It is one of the most popular and efficient kitchen appliances in modern kitchens.It has the advantages of good smoke absorption,high functional integration and small size.In recent years,integrated stoves have developed rapidly and popularized.The multi-blade centrifugal fan has the advantages of small size,high flow coefficient and pressure coefficient,and is often equipped inside of the integrated stove air duct as a power source.With the rapid development of integrated stoves,the research on the internal air duct of integrated stoves is lacking,and it is still in the initial stage of research and development.But the higher requirements for its air volume,pressure rise,efficiency and noise are proposed.Therefore,it is of great significance to improve the working environment of modern kitchens by explore and improve the flow field and sound field characteristics of the integrated stove air duct system and internal multi-blade centrifugal fan.The X7 Z integrated stove air duct and its multi-blade centrifugal fan provided by the cooperative enterprise are the research objects.The numerical calculation and experiment methods are used to study the performance and noise of the integrated stove air duct system and its multi-blade centrifugal fan.The performance and flow field characteristics of the integrated stove air duct system are analyzed by three-dimensional numerical calculation.The acoustic analogy equation is used to calculate the transient large eddy simulation of the multi-blade fan under design conditions,and fan noise and spectral characteristics predicts by the Ffowcs Williams & Hawkings receivers.In this paper,the integrated stove air duct and its multi-blade centrifugal fan are modified by different geometric parameters,including the bellow,blade and tongue structure.The influences of the geometric parameters of the integrated stove air duct on the internal flow field and sound field are explored,which provides a reliable theoretical basis for the optimal design of the integrated stove duct system.The main research contents and conclusions are as follows:(1)Effects of the clockwise and anticlockwise layout of the outlet bellow on the internal flow and aerodynamic performance of integrated stove were explored.The numerical results show that the clockwise connection can effectively reduce the gradient of the internal pressure,vorticity and turbulent kinetic energy distribution of the integrated stove,suppress the vortex structure of the integrated stove exit duct,and reduce the internal flow loss.Experimental results show that a clockwise connection can improve the aerodynamic load of the integrated stove.(2)Based on a rational design in the duct system,the inlet bellow of the integrated stove adopt closed structure,and the outlet bellow adopt vane type structure,which effectively improves the stability of the airflow at junctions.It is found that the coupling design of the air inlet and outlet bellows is used to realize the regulation of the internal flow field of the integrated stove,which makes the flow distribution inside the air duct more uniform and reduces the flow loss.Under the same flow rate and rotational speed conditions,the best performance improvement effect of the integrated stove air duct system is that the total pressure is increase from 173.7Pa to 188.7Pa with the growth rate of 8.6%,and the total pressure efficiency is increased by 5.4%,which achieve increased pneumatic load on the integrated stove.Experimental results show that the noise of the integrated stove is almost unchanged after optimization,and the increase of the aerodynamic load of the integrated stove can reduce the integrated fan noise by around 1.0 dB by reducing the speed of the centrifugal fan while maintaining the same flow rate and pressure conditions.(3)Based on coupled bionic design,influence of the leading and trailing edges of blades on the internal flow and the generated radiated noise of the integrated stove was studied,the results show that the coupled bionic blades effectively control the noise of the integrated stove duct,and does not affect the aerodynamic performance of the integrated stove.The blade design of the wave leading edges and fly-wing trailing edges reduces the mutual interference between the blades and the dynamic and static interference between the blades and tongue,which reduces the discrete noise of fan.(4)The effect on the performance and sound pressure level of the multi-blade centrifugal fan used for integrated stove was studied by changing the cut-off structure.It is verified by the experiment of fan that the noise numerical method based on acoustic analogy method of FW-H equation can effectively predict the noise of multi-blade centrifugal fan by using the numerical method of large eddy simulation.The numerical results show that the stepped tongue models can improve the internal flow field structure of the centrifugal fan,making the internal flow distribution more uniform and reducing the flow loss.At the same time,the experimental results also show that under the same flow rate and rotational speed conditions the design of the stepped tongue effectively improves the performance and controls the tonal noise of the multi-blade centrifugal fan,and the model of the double-stepped tongue has better optimal effect than the model of the single-stepped tongue.