The influence of housing on the internal flow of a cross flow fan impeller

A 2D numerical model is used in order to assess the role of vortex wall/stabilizer over eccentric vortex inside of a cross flow fan impeller. The simulation was performed by using FLUENT code with RNG k-ε turbulence model. Three values for the inlet setting angles of the impeller were selected β₁ = 15⁰, 25⁰, 35⁰ and three positions for the vortex wall/stabilizer. Therefore, 3 impellers (RI, RII, RIII) were simulated for each three positions of a shaped vortex wall (A, B, C). Best results are reported for the impeller RI (β₁ = 15⁰). For this case the eccentric vortex is acting mostly outside the impeller for open positions of the wall/stabilizer A and B. As a result the region of low pressure is extended outside the impeller favoring flow recirculation. The C position of the vortex wall (lowest distance between housing and the impeller) provides the highest value for the average outlet velocity v_m even the eccentric vortex axis is more close to internal impeller region. The results obtained for impeller RI shows that it is not necessary that eccentric vortex axis should be positioned outside the impeller for best performances of the fan. Also, increasing the inlet setting angle of the cross fan impeller (β₁) creates high asymmetric velocity profile at outlet section of the fan casing and decreases the outlet average velocity.