RE: PSV Tailpipe, 45 Degree Cut?

Additional Comments on Beveled Relief Tail Pipes:

Notes in the eng-tips thread mentioned by Paul below give many thoughts on the subject:

Dr. Hans Bos (author of BOS Fluids) added the following, which I thought might be useful, and so wanted to pass along:

1. Organ pipe beveling has a small effect on standing wave frequency and this is figured into the tuning process of the pipe/organ.
2. The lateral load component at the tail pipe exit is equal to the normal thrust force multiplied by the sine of one half of the bevel angle.
3. The lateral load component at the end of a relief tail pipe is often introduced to reduce the bending moment on the header. The bevel angle is adjusted so that the exhaust thrust force acts along a line that passes through the centerline of the manifold or header.
4. Beveled ends break the flow symmetry at the exit, disturbing the periodic shedding of stable torus type vortices that contribute to noise strength. Rotational symmetry in the diamond shaped shock wave/expansion pattern downstream of the tail pipe, in combination with the convection of vortices is considered the origin of the screeching noise in jet exhausts.

Regards,

Tony

From: <a href="/group/PipingDesign/post?postID=89PKmLnZtqx1VNp-HWkCmA6H5UXIlXqNvRgXKAM3fdbGA-U3qb8QfZV7w2cNxjairrEavQlEXQZS8_Q5DWzqQxXtdX_frx0">PipingDesign@yahoogroups.com</a> [mailto:<a href="/group/PipingDesign/post?postID=89PKmLnZtqx1VNp-HWkCmA6H5UXIlXqNvRgXKAM3fdbGA-U3qb8QfZV7w2cNxjairrEavQlEXQZS8_Q5DWzqQxXtdX_frx0">PipingDesign@yahoogroups.com</a>] On Behalf Of Paul Bowers
Sent: Friday, February 09, 2007 9:13 PM
To: <a href="/group/PipingDesign/post?postID=89PKmLnZtqx1VNp-HWkCmA6H5UXIlXqNvRgXKAM3fdbGA-U3qb8QfZV7w2cNxjairrEavQlEXQZS8_Q5DWzqQxXtdX_frx0">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] PSV Tailpipe, 45 Degree Cut?

Sakarya, Hasim (H) wrote:
> Paul,
> Could you please comment on to what will happen to the horizontal
component of velocity if the pipe end is square cut at 90 degrees.
> Thanks and kind regards,

I quoted NozzleTwister from
<a href="http://www.eng-tips.com/viewthread.cfm?qid=156173&page=6">http://www.eng-tips.com/viewthread.cfm?qid=156173&page=6</a> <<a href="http://portal.mxlogic.com/redir/?kXLTs7eecfCQXLTp7e9If6M0nM8BVOmFO-6puo">http://portal.mxlogic.com/redir/?kXLTs7eecfCQXLTp7e9If6M0nM8BVOmFO-6puo</a> Cjz-EtpRkAbigehvsh7cJ104bqhYVMTvHFETKOyYUqejtPtfxetiWqbXzz1t5dMsMnhh78T7 fc8zyYWMb7bqSva7bwGfPrz2D4oRrmFNritqYKrho79CzASyyehKeuojKro76MnWhEwdbomA Ja14e-Ayc3iWq80Ic1AQg0Dp7HimY0Ph0M-q80XOcvYQg2jsOhKvxYY1NJ4SyedFTvKOeshv sdNiHu8Pur>

Maybe an image is usegul in order to illustrate exactly what I mean:

<a href="http://www.pipingdesign.com/graphics/psv_45_outlet.jpg">http://www.pipingdesign.com/graphics/psv_45_outlet.jpg</a> <<a href="http://portal.mxlogic.com/redir/?FTvKUessovdFTvKOesjoudw0BFbiwhg-AycenM">http://portal.mxlogic.com/redir/?FTvKUessovdFTvKOesjoudw0BFbiwhg-AycenM</a> z7lysHkNqxAlov5qJPf-v2aN4TvHFETKOyYUqejtPtfxetiWqbXzz1t5dMsMnhh78T7fc8zy YWMb7bqSva7bwGfPrz2D4oRrmFNritqYKrho79CzASyyehKeuojKro76MnWhEwdbomAJa14e -Ayc3iWq80Ic1AQg0Dp7HimY0Ph0M-q80XOcvYQg2jsOhKvxYY1NJcSyedFTvKOeshvsdNiH u8Pur>

In neither of these options do I see a benefit in cutting the end of the

outlet pipe at an angle, but maybe I'm missing something important.

Paul

[Non-text portions of this message have been removed] Received on Wed Feb 14 18:59:00 2007