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An Experimental Investigation of the Gasdynamic Performance of Gun Bore Evacuators Mounted on 155-mm Self-Propelled Howitzers.

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Final rept.,

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The charge and discharge cycles of the 155-mm gun bore evacuator have been investigated at the Rensselaer Polytechnic Institute RPI High Pressure Shock Tube and Steady-State Flow Facilities. To test the charge and discharge phases in the high pressure shock tube, a 65 percent scale model of the bore evacuator is installed on the end of the shock tube. Thin plastic diaphragms are placed over the evacuator charge and discharge ports. The pressure behind the Mach 1.89 incident shock wave is 91 psia, and the flow Mach number is 0.89. The evacuator pressure is varied to obtain ratios of the initial evacuator pressure- to-bore pressure up to 2300. The charge coefficient for the charge ports in the baseline configuration is 0.29. With no restriction at the exit of the charge ports, the charge coefficient is approximately 0.40. The charge coefficient for the angled discharge ports varies from 0.51 at a PP, of 4 to 0.58 at a the of 1570. During the charge phase with high pressure ratios across the evacuator ports, shock waves with high temperatures behind the waves are present in the evacuator. The discharge coefficient for the ejector ports is approximately 0.72 for an evacuator pressure range of 50 to 195 psia. A 33 percent scale model of the 155-mm gun bore evacuator is installed in the RPI Steady-State Flow Facility, and the performance of a model with six staggered ejector ports is compared to the baseline configuration. The staggered ejector configuration results in a gain of approximately 20 percent in the mass flow augmentation ratio over test pressures from 1 to 84 psig.

Subject Categories:

  • Guns
  • Fluid Mechanics

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