Pressure losses in curved ducts: single bends.
Abstract:ESDU 83037 gives comprehensive data for the estimation of pressure loss in circular-arc bends taking account of the effects of bend radius ratio and angle, upstream and downstream duct lengths, surface roughness, cross-sectional shape and Reynolds number. The data are in the form of a general equation for which a graphical solution is also provided. For the common case of a 90 degree, smooth bend of circular or square section a direct graphical presentation of pressure loss coefficient is given. Reanalysis of the available information for single and 90 degree composite mitre bends has shown that, contrary to the usual assumption, surface roughness has a significant effect on pressure losses. These data are given graphically in terms of a reference pressure loss coefficient and correction factors for Reynolds number and roughness effect. Approximate data are provided for "standard pipe bends" for use where little detail of the bend geometry is available and sources of data for other bend types (for example, bends where the inner and outer walls are not concentric) are referenced. The effect of guide vanes or splitters in bends is considered and a simple design for use in mitre bends is given. All the information results from correlations of experimental data drawn from a wide range of sources. A practical worked example is included, and data on straight pipe friction factors and effective surface roughness of various pipe materials are given. The method for circular-arc bends is provided as a computer program, ESDUpac A8337.
- Cascades of Guide Vanes
- Curved Ducts
- Curved Pipes
- Curved Tubes
- Guide Vanes
- Pipe Bends
- Pressure Drop in Internal Flow
|Data Item ESDU 83037|
The Data Item document you have requested is available only to subscribers or purchasers.
- Subscribers login here.
- If you are not an ESDU subscriber you can
- find out how to subscribe, or
- purchase this Data Item from the Standards Store.
This Data Item is complemented by the following software:
This program is only available to subscribers.
The graphs listed below are available only to subscribers.
- Subscribers login here.
- If you are not an ESDU subscriber find out how to subscribe.
This Data Item contains 22 interactive graph(s) as listed below.
|Figure 1||Friction factor for straight pipes|
|Figure 2||Boundary layer between long and short circular-arc bends|
|Figure 3a||Transition region for flow in long circular-arc bends|
|Figure 3b||K's,G for long, smooth circular-arc bends|
|Figure 3c||Surface roughness correction factor phi4 for long circular-arc bends|
|Figure 4a||Ks,G for short, 90 degree circular-arc bends in laminar flow|
|Figure 4b||Ks,G for smooth, short circular-arc bends in turbulent flow|
|Figure 5a||Kb for short circular-arc bends in turbulent flow|
|Figure 5b||KC for short, 90 degree circular-arc bends in turbulent flow|
|Figure 5c||Kd for short, 90 degree circular-arc bends in turbulent flow|
|Figure 5d - Part 1||Downstream tangent length correction to K'd for short, 90 degree circular-arc bends|
|Figure 5d - Part 2||Downstream tangent length correction to K'd for short, 90 degree circular-arc bends|
|Figure 5e||Bend angle correction to K'd for short circular-arc bends|
|Figure 6a||Basic pressure loss coefficient for single mitre bends|
|Figure 6b||Basic pressure loss coefficient for composite mitre bends, theta = 90 degrees|
|Figure 7a||Reynolds number correction for mitre bends (for rough bends use factor Phi4 also)|
|Figure 7b||Roughness correction for mitre bends (use factor Phi1 also)|
|Figure 7c||Roughness correction for mitre bends (use factor Phi1 also)|
|Figure 8a - Part 1||Guide vanes or splitters in circular-sectioned circular-arc bends. Optimum location for one guide vane|
|Figure 8a - Part 2||Guide vanes or splitters in circular-sectioned circular-arc bends. Optimum location for two guide vanes|
|Figure 8b||Guide vanes or splitters in circular-sectioned circular-arc bends. Reduction in loss coefficient for vanes at optimum location Ks,G (with vanes) = Ks,G (without vanes) x Phi6|
|Figure 9||Approximate Ks,G values for 90 degree standard pipe bend fittings|