GB2292419A

GB2292419A - Reducing the flow resistance of curved passages

Info

Publication number: GB2292419A
Application number: GB9516665A
Authority: GB
Inventors: Peter Fisher
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-08-15
Filing date: 1995-08-15
Publication date: 1996-02-21
Anticipated expiration: 2015-08-15
Also published as: GB9516665D0; GB9416438D0; GB2292419B

Abstract

A flow passage 10, particularly the fuel/air inlet passage of an internal combustion engine, has a flow affecting member 1 located within its bore with an elongate vane 4 which directs the flow towards the inside 11 of a flow passage bend. The vane 4 is carried from a base 2 by a transverse web 3 and is shaped and dimensioned to increase the flow capacity of the passage for a given pressure drop. The width of the vane 4 is between 15 and 30% of the passage width. <IMAGE>

Description

FLOW PASSAGE AND FLOW CONTROL MEMBER The present invention relates to a flow passage, particularly but not exclusively the fuel/air inlet of a reciprocating internal combustion engine, and to a flow control member for such a flow passage.

Very surprisingly it has been found that the flow capacity for a given pressure drop of a fuel/air inlet passage of such an engine can be increased significantly by locating a longitudinally extending tongue within the bore of the passage, the tongue being inclined toward the inside of a bend in the passage. The invention is clearly distinguished from arrangements such as those disclosed in US-A-3,868,940 and GB-A-2,105,783 which deliberately increase turbulence but at the expense of flow capacity. Without wishing to be bound by theory, it is suggested that the present invention works by reducing the swirl and resulting turbulence of gas in the flow passage and by guiding the gas over the surface of the tongue toward the inside of the bend where there is a shorter flow path.

The application of the invention is not restricted to internal combustion engines however, and accordingly in one aspect the invention provides a flow passage having a bend and a longitudinally extending tongue located within the bore of the passage, said tongue being inclined toward the inside of the bend and being shaped and dimensioned to increase the flow capacity of the passage for a given pressure drop.

Preferably the passage includes a portion tapering toward said bend and said tongue is located within said tapered portion.

Desirably the width of said tongue is less than or equal to 30% of the diameter of the bore of the portion of the passage surrounding said tongue.

Preferably said width is less than 25% of said diameter. More preferably said width is from 15% to 25% of said diameter. If the bore of the passage is non-circular in cross section. then the diameter referred to above is that diameter which is parallel to the centre line of the tongue.

In another aspect the invention provides a flow control member comprising a base portion. an elongate tongue portion which extends at an inclination to said bore portion and a web portion connecting said tongue portion to said base portion, the web portion being transverse to the tongue portion and base portion and the flow control member being adapted for increasing the flow capacity of a flow passage for a given pressure drop when longitudinally aligned in the bore thereof with the base portion mounted on the inner wall of the passage.

Preferred features are defined in the dependent claims.

Preferred embodiments are described below by way of example only with reference to Figures 1 to 8 of the accompanying drawings, wherein: Figure 1 is a cross-section of a cylinder head of a reciprocating internal combustion engine having a flow passage in accordance with the invention; Figure 2 is a transverse cross-section through the manifold of the arrangement of Figure 1, showing the flow control member in end elevation; Figure 3 is a further transverse cross-section through the manifold, having the flow control member in top plan view; Figure 4 is a side elevation of the flow control member of Figure 1; Figure 5 is a cross-section taken on line V-V of Figure 4; Figure 6 is a cross-section taken ofn line VI-VI of Figure 4;; Figure 7 is a side elevation of another flow control member in accordance with the invention, and Figure 8 is a side elevation of a further flow control member in accordance with the invention.

Referring to Figure 1, a cylinder head 6 and manifold 5 of a single overhead camshaft reciprocating internal combustion engine is shown. the cylinder head 6 including a bore 7 for a poppet valve (not shown) and a threaded bore 8 for a spark plug (not shown). A fuel/air inlet passage 10 leads to a combustion chamber 9 and includes a bend at its downstream end, having a short turn" or inside portion 11 and a long turn" or outside portion 12.

Immediately upstream of this bend, a flow control member 1 is mounted within the tapered bore of inlet manifold 5, and comprises a tongue 4 (Figures 2 and 3) which extends longitudinally and is inclined towards the inside 11 of the bend. The tongue 4 is carried on a transverse web 3 (Figure 2) which is generally triangular in side elevation and extends from a flat longitudinally extending base 2 (FIgures 2. 3 and 4). Base 2 is provided with fixing means in the form of three threaded holes 14 (Figure 1) of which the middle and front holes, receive bolts 13 which are fitted through the manifold wall. The bolts may alternatively be received into the middle and rear holes 14 so that the flow control member is located downstream of the position shown in Figure 1.

As shown in Figures 4, 5 and 6, the web 3 tapers longitudinally in the upstream direction and expands radially to merge into the tongue 4 and base 2.

The width w (Figure 2) of the tongue 4 is 8mm. i.e. about 20% of the bore diameter of 40mm.

The radius r of the inside portion 11 of the bend (Figure 1) is about 7mm and the other dimensions in Figure 1 are to scale.

The cylinder head of Figure 1 is based on a cylinder head of a 2000 cc 4cylinder single overhead camshaft Fords engine dating from about 1980 and this engine developed 71kW (95b.h.p) in unmodified form. Essentially this power is limited by the airflow capacity of the fuel/air inlet passage 10, which was measured at 39.1 litres/second (83 ft3/min) at a cam lift of 12.7 mm (0.5 inch) at a pressure of 2.49kPa (10" water pressure) using Superflow) flowbench a supplied by Superflow Corporation of Colorado Springs. USA.

By building up the profile of the inside 11 of the bend to that shown in Figure 1, and by selective metal removal from the bore of passage 10 to give the section shown in Figure 1. it was possible to increase the power to 146kW (196 b.h.p.) corresponding to a flow capacity under the above conditions of 61.2 litres/second (130fat3 /min) per cylinder.

On locating the flow control member 1 within the bore of the manifold, a further improvement of flow capacity to 69.2 litres/second (147fit3' min) under the above conditions was achieved, representing an improvement of 13%.

According to data provided by Superflow Corporation, each cubic foot/minute improvement in airflow per cylinder (1 c.f.m. = 0.47 litres/second) will result in a potential increase of 0.43 b.h.p. per cylinder (1 b.h.p. = 0.746kW).

Hence the above embodiment of the invention enables a significant increase in power to be obtained. However, it is believed that the invention is also applicable to non-reciprocating internal combustion engines such as gas turbines for example and to other engines (not necessarily prime movers) having gas flow passages.

Figure 7 shows a further embodiment 1l in which the tongue 4' extends further in the upstream direction from the base 21 and the web 3' is similar to the web 3 of the preferred embodiment.

The embodiment 1" of Figure 8 includes a tongue 411 which is swept back still further, and has a clearly defined flat base portion 211 and a web 3 which is similar to web 3.

Claims

1. A flow passage having a bend and a longitudinally extending tongue located within the bore of the passage. said tongue being inclined toward the inside of the bend and being shaped and dimensioned to increase the flow capacity of the passage for a given pressure drop.

2. A flow passage according to Claim 1. which includes a portion tapering towards said bend and wherein said tongue is located within said tapered portion.

3. A flow passage according to Claim 1 or Claim 2, wherein the width of the said tongue is less than or equal to 30% of the diameter of the bore of the portion of the passage surrounding said tongue.

4. A flow passage according to Claim 3, wherein said width is less than 25% of said diameter.

5. A flow passage according to Claim 4, wherein said width is from 15% to 25% of said diameter.

6. A flow passage according to any preceding Claim, wherein said tongue is carried on a web portion which is transverse to the tongue and extends radially from the tongue to an inner wall of said flow passage.

7. A flow passage according to Claim 6, wherein said web portion expands in the radial direction to a base portion adjacent said inner wall and tapers in the longitudinal direction away from said bend.

8. A flow passage according to any preceding Claim, wherein said tongue is formed by a discrete flow control member which is provided with fixing means for attaching it to the bore of said flow passage.

9. A flow passage according to Claim 9, wherein said fixing means enables the longitudinal position of said flow control member to be adjusted.

10. A flow-control member comprising a base portion, an elongate tongue portion which extends at an inclination to said base portion and a web portion connecting said tongue portion to said base portion, the web portion being transverse to the tongue portion and base portion and the flow control member being adapted for increasing the flow capacity of a flow passage for a given pressure drop when longitudinally aligned in the bore thereof with the base portion mounted on the inner wall of the passsage.

11. A flow-control member substantially as described hereinabove with reference to Figures 4, 5 and 6 or Figures 7 and 8 of the accompanying drawings.

12. An engine having a gas flow passage with a bend therein and a longitudinally extending tongue located upstream of the bend, the tongue being inclined towards the inside of the bend and being shaped and dimensioned to increase the gas flow capacity of the passage for a given pressure drop.

13. An engine according to Claim 12, wherein said passage is tapered towards the downstream direction.

14. An engine according to Claim 12 or 13 which is an internal combustion engine.

15. An engine according to Claim 14 which is a reciprocating internal combustion engine and wherein said tongue is mounted within the bore of a fuel/air inlet passage.

16. An internal combustion engine according to Claim 15, wherein said tongue is located within the bore of a tapered inlet manifold.

17. An internal combustion engine according to any of Claims 14 to 16, wherein said passage is as claimed in any of Claims 3 to 9.

18. A reciprocating internal combustion engine having a fuel/air intake arrangement substantially as described hereinabove with reference to Figures 1 to 3, optionally as modified in accordance with Figures 4, 5 and 6 or Figure 7 or Figure 8 of the accompanying drawings.