Negative Total Pressure Loss Coefficient near the casing in axial compressor

mitra22 · August 24, 2013, 09:23

Hi!
My question is specific to CFX Turbomachinery, axial flow compressor.

I am trying to plot the circumferentially averaged value of total pressure loss (occurred between the stator inlet and stator outlet stations) along the annulus height (from Hub to casing),i.e along the hub to shroud line.

Total Pressure Loss Coefficient= (P03-P02)/(rho*V^2);

But i find that very near to the casing i.e. at nearly 99.5% of annulus height, i find an increase in pressure or a small negative pressure loss coefficient,which means energy is being created,which does not happen within a stator passage.Does it mean that theres an energy transfer/migration from somewhere to the viscous layer nearby the casing region? I donot know how to explain the negative number(rise in total pressure at a single point in the viscous region).The entropy rise is positive at that location , obeying thermodynamics well

Please ,if any one has any idea of where i am going wrong,let me know.

suryanshsingh · December 15, 2017, 23:34

Hi, I am also facing a similar problem at rotor hub, the loss coefficient is coming negative from 0 to .15 span. were you able to find any solution to your problem?

August 24, 2013, 09:23	Negative Total Pressure Loss Coefficient near the casing in axial compressor	#1
mitra22 New Member AGNIMITRA Join Date: Jan 2013 Posts: 8 Rep Power: 13	Hi! My question is specific to CFX Turbomachinery, axial flow compressor. I am trying to plot the circumferentially averaged value of total pressure loss (occurred between the stator inlet and stator outlet stations) along the annulus height (from Hub to casing),i.e along the hub to shroud line. Total Pressure Loss Coefficient= (P03-P02)/(rho*V^2); But i find that very near to the casing i.e. at nearly 99.5% of annulus height, i find an increase in pressure or a small negative pressure loss coefficient,which means energy is being created,which does not happen within a stator passage.Does it mean that theres an energy transfer/migration from somewhere to the viscous layer nearby the casing region? I donot know how to explain the negative number(rise in total pressure at a single point in the viscous region).The entropy rise is positive at that location , obeying thermodynamics well Please ,if any one has any idea of where i am going wrong,let me know.

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December 15, 2017, 23:34		#2
suryanshsingh New Member Suryansh Join Date: Dec 2017 Posts: 2 Rep Power: 0	Hi, I am also facing a similar problem at rotor hub, the loss coefficient is coming negative from 0 to .15 span. were you able to find any solution to your problem?