CH-32

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Unformatted text preview: Given : D = 140 mm = 0.14 m ; L = 270 mm = 0.27 m ; Power = 8.25 kW = 8250 W ; N = 475 r.p.m ; p = 3.5 N/mm2 ; l = 150 mm = 0.15 m ; θ = 160° ; w = 3 N First of all, let us find out dimensions of the valve as discussed below : Size of the valve port Let dp = Diameter of the valve port, and π 2 ap = Area of the valve port = 4 (d p ) We know that area of the piston, a= π2π D = (0.14)2 = 0.0154 m2 4 4 and mean velocity of the piston, 2 L N 2 × 0.27 × 475 = = 4.275 m / s 60 60 From Table 32.3, let us take the mean velocity of the gas through the port (vp) as 40 m/s. We know that ap .vp = a.p v= π (d )2 40 = 0.0154 × 4.275 or 31.42 (dp)2 = 0.0658 4p ∴ (dp)2 = 0.0658 / 31.42 = 2.09 × 10–3 or dp = 0.045 m = 45 mm Ans. Maximum lift of the valve We know that maximum lift of the valve, dp 45 = h= = 15.9 say 16 mm Ans. 4 cos α 4 cos 45º ...(Taking α = 45º) Thickness of the valve head We know that thickness of valve head, t = k · dp 3.5 p = 0.42 × 45 = 4.72 mm Ans. σb 56 ...(Taking k...
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This note was uploaded on 09/30/2012 for the course MECHANICAL 403 taught by Professor A.thirumoorthy during the Spring '11 term at Anna University Chennai - Regional Office, Coimbatore.

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