Key_Learnings_1

  1. Thrust direction
    At normal operating conditions and during surge net thrust is towards compressor. During choke, mostly towards turbine or balanced.
  2. Section 0, Diffuser radius
    • Increase in section zero area and diffuser radius, is seen to improve performance at higher mass flow rates and increase flow capacity for each speed line, before the impeller reaches choke condition
    • For A118J73, at the same diffuser radius ratio (1.5 or 1.65 or 1.8), increasing section zero area (7sq.cm to 22sq.cm to 26.5sq.cm), maintaining diffuser gap of 80% tip width, lead to higher diffuser loss near surge and lower diffuser loss near choke. For the same section zero area, increase in diffuse radius led to lower cover loss.
    • However, for D79J68, increase in section zero area from 12.76 to 17sq.cm, with diffuser radius ratio of 1.73, led to an detrimental effect on performance due to tongue interaction and the outlet connection bent towards inlet
  3. Squareness ratio
    Reduction in squareness ratio from 71 to 68 shifts the flow envelope to the left, thereby improving performance near surge with reduced choke flow and performance at near choke
  4. MWE
    MWE slot shift towards compressor Inlet by 1.5mm has insignificant effect on performance (MFP and T-T Efficiency) but has considerable effect on MWE mass flow rate at all speeds. Test data showed change in surge margin At higher speed.
  5. Vaned diffuser
    For the same power rating, vaned diffuser helps improve PR by xxx along with some HCF risk
  6. Area Schedule
    Change in scroll area schedule within 4% with same section zero area causes insignificant change in compressor performance.
  7. Inlet shape
    Use of bell mouth (25.33mm from impeller shroud tip) or conical shape (20.71mm from impeller shroud tip) at compressor inlet did not have any impact on efficiency and performance
  8. Clearance
    Non linear clearance schedule with same FWC, IRC did not have any effect on performance
  9. Curved diffuser
    Curved diffuser with min. width of 3.46mm (60% Tip width) led to improvement in performance at surge for all speed lines and reduction in choke margin for lower speed lines
  10. Bend diffuser
    Bent in inlet pipe at a distance of xx from the LE of the impeller did not have significant effect on performance
  11. Vaned diffuser
    • For the same power rating, vaned diffuser helps improve PR by xxx along with some HCF risk
    • Staggering diffuser vane (with ~3 times thickened LE) and modifying its beta to match throat area as in base design helped in matching performance of modified comp stages with baseline comp stage.
    • Increase in diffuser vane throat area increased performance linearly at choke and gradually at surge
  12. Wall roughness
    • Compressor scroll 32 microns
    • Turbine housing 125 microns
  13. Impeller physics
    Lower pressure ratio but better efficiency means impeller is diffusing more than imparting work to fluid, lower outlet velocity
  14. Impeller design - hub to shroud variation
    Hub to shroud variation cause distortion in flow spanwise leading to affect work transfer as well as diffusion

    This variation in any parameter must be reduced
  15. Diffuser outlet velocity
    Higher swirl at diffuser outlet can help align flow better to the scroll and thus reduce losses

    Diff gap can aid in pressure recovery and also making flow more circumferential into the cover

    Higher radial velocity at diffuser outlet will cause more vortex formation
  16. Blend
    His unique profound approach to self improvement ****** scientific theories and perfect logic with Vedic scriptures
Author
ganeshykr
ID
355505
Card Set
Key_Learnings_1
Description
Compressor
Updated