GB2502061A

GB2502061A - Turbocharger with tubercles on the nozzle ring vanes

Info

Publication number: GB2502061A
Application number: GB1208396.0A
Authority: GB
Inventors: Aaron William Costall
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2012-05-14
Filing date: 2012-05-14
Publication date: 2013-11-20
Also published as: GB201208396D0

Abstract

A turbocharger with a nozzle ring of vanes in the turbine and/or compressor provided with tubercles, as found on the fins of humpback whales, on the proximal edge of the vanes to improve lift efficiency and stall resistance. Preferably there are between 8 and 15 vanes with 10 tubercles on each. The vanes may be fixed or variable geometry.

Description

IMPROVEMENTS IN TURBOCHAROERS

TECHNICAL FIELD

The disclosure relates to improvements in turbochargers for use with engines such as internal combustion engines, and more particularly to such a turbocharger having stationary vanes in the turbine and/or oompressor provided with tubercles.

BACKGROUND

Internal combustion engines are supplied with a mixture of air and fuel for combustion within the engine to generate meohanioal power. To maximize the power generated by this combustion process, the engine is often eguipped with a turbocharged fluid (usually air) induction system.

An internal combustion engine may therefore include one or more turbochargers for compressing the fluid to be supplied to one or more combustion chambers within corresponding combustion cylinders. Each turbocharger typically includes a turbine, driven by exhaust gases from the engine, and a compressor driven by the turbine. The compressor receives the fluid to be compressed and supplies the compressed fluid to the combustion chambers. The fluid compressed by the compressor may be in the form of combustion air only, or may be a mixture of fuel and combustion air. Through the use of a turbocharger, the power available from an engine of a given size can be increased significantly. Thus, a smaller, less expensive engine may be used for a given power requirement and power losses due to, for example, changes in altitude, can be compensated for.

The fuel energy conversion efficiency of an engine depends on many factors, including the efficiency of the engine' s turbocharger.

Sizing a turbocharger for proper performance under all engine operating conditions can be difficult. In an exhaust gas turbocharger, exhaust gas flow and turbine design determine turbine performance, and thereby compressor performance and turbocharger efficiency. Vanes in the inlet throat or outlet nozzle of the turbine oan be used to influence flow characteristics through the turbine, and thereby the turbine power generated for a given exhaust gas flow.

If the engine is to be operated at, or near, full load during most of its operating cycle, it is not difficult to design the turbocharger for efficient performance. However, if the engine is to be operated at significantly less than full load for extended periods of time, it becomes more diffioult to design a turbocharger that will perform well throughout the operating range of the engine. Desirably, the turbocharger will provide the reguired level of pressure boost, respond quickly to load changes, and function efficiently under both high load and low load conditions.

For an engine having a wide range of operating load, it has been known to size the turbine for proper performance under full load conditions. A problem with this approach is that the turbocharger responds slowly at low speed, and the boost pressure available at low engine speeds is minimal. As an alternative, it has been known to provide a turbine design that exceeds the power requirements at full load, and to use a waste gate to bypass exoess exhaust gas flow after the turbocharger has reached the desired boost level. An oversized turbine of this type will provide greater boost at lower load conditions, and will respond more guickly at lower speeds, but engine back pressure is increased and the energy in the bypassed exhaust flow is wasted.

It is also known to control turbocharger performance by controlling exhaust gas flow through the turbine of the turbocharger. Controllable vanes in the turbine throat and/or nozzle exit have been used to control turbine efficiency, and thereby turbocharger performance. Pivotable vanes oonneoted by linkage to a oontrol ring have been used.

Rotation of the ring changes the vane angle, and thereby the flow characteristics of the exhaust gas through the turbine.

Many of the known variable nozzle designs are complex, having numerous pivotal connections and complex linkages.

Such complex designs may be prone to failure and wear.

The present disclosure is therefore directed to

improving turbocharger performance to reduce the problems identified above.

Recent research in the field of aerodynamics has lead to the discovery that where the edges of airfoils are provided with tubercies, as found along the fins of humpback whales, the airfoils have improved lift efficiency and stall resistance. Similarly the use of such tubercles along the edges of turbine blades, leads to an increase in power, a decrease in noise and otherwise improved performance. US-A- 2009/0074578 describes how the use of such tubercles on the leading edge of a turbine/oompressor blade leads to improved efficiency in the capture of force from wind or other moving fluids. US-B-6,431,498 describes the use of scalloped tuberole like protrusions along the leading edge of a wing to enhance lift, reduce drag and to postpone (or inhibit) the onset of stall. However in each of these applications the tubercles/protrusions have been applied to a rotating flow surface. The present disclosure arises from a new application of the phenomenon described in these two documents to stationary flow surfaces.

SUMMARY

The present disclosure therefore relates to a

turbooharger for an engine comprising a compressor and a turbine, said turbine comprising a nozzle ring provided with a plurality of vanes, said vanes having a proximal end and a distal end, the proximal end of each vane being located at an outer periphery of the nozzle ring and the distal end being located inwardly thereof, wherein the proximal end of the vanes are provided with at least one tubercls.

The present disclosure also relates turbocharger for an engine comprising a compressor and a turbine, said compressor comprising a nozzle ring provided with a plurality of vanes, said vanes having a proximal end and a distal end, the proximal end of each vane being located at an outer periphery of the nozzle ring and the distal end being located inwardly thereof, wherein the proximal end of the vanes are provided with at least one tubercle.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic diagram of an internal combustion engine having a turbocharger; Figure 2 is perspective view, with parts omitted for clarity, of a turbine of the turbocharger of the internal combustion engine of Figure 1; Figure 3 is a plan view of a nozzle ring of the turbocharger of Figure 2; and Figure 4 is a perspective view of a nozzle vane of the nozzle ring of Figure 3.

DETAILED DESCRIPTION

Referring now to Figure 1 of the drawings, this illustrates a very simple internal combustion engine 10, including a turbocharger 11. The internal combustion engine includes a plurality of combustion cylinders 12 housed in a crankcase 13. Each combustion cylinder 12 is fluidly coupled with an intake manifold 14 and with an exhaust manifold 15. while single intake and exhaust manifolds 14, 15 are shown, it should be understood that more than one intake or exhaust manifolds 14, 15 may be used, with each intake or exhaust manifold 14, 15 coupled to a plurality of combustion cylinders 12. A fuel, such as diesel fuel, or fuel air mixture is introduced into each combustion cylinder 12 and combusted therein, in a known manner.

Turbocharger 11 includes a turbine 16, and a compressor 17. Compressor 17 includes a compressor inlet 18 and a compressor outlet 19. Compressor inlet 18 receives combustion gas from a source such as ambient air, and compressor outlet 19 supplies compressed combustion gas to the intake manifold 14 of the engine 10 via a charge air conduit 20. The combustion gas may pass through an air filter 21 before it passes into the compressor 17. The compressed combustion gas may also be passed through a charge air cooler 22 before it passes into the intake manifold 14. Whilst a single turbocharger 11 is shown, the engine 10 may have a plurality of turbochargers 11.

Compressor 17 includes a compressor wheel (not shown) mounted on a turbocharger shaft 23 in a known manner. Whilst a single compressor 17 is shown, more than one compressor 17 may be provided, each with a compressor wheel mounted on shaft 32, and having an inter-stage duct connecting the compressors 17 in series.

Turbine 1 has a housing 30 which includes a turbine inlet 24 and a turbine outlet 25. A turbine wheel 29 (see Figure 2) is mounted on the turbocharger shaft 23 inside the turbine housing 30. Whilst a single turbine 16 is shown, more than one turbocharger 16 may be provided, each with a turbine wheel 29 mounted on the shaft 32, and having an inter-stage duct connecting the turbines 16 in series. The turbine inlet 24 is fluidly connected with the exhaust manifold 15 and the turbine outlet 25 is fluidly connected to an exhaust system 26 of engine 10, which may include an after treatment device 27 which removes combustion products from the exhaust gas stream and one or more mufflers 28 to dampen engine noise, before the exhaust gas is discharged to an ambient environment.

Inside the turbine housing 30, the turbine inlet 24 is fluidly connected one or more inlet gas passages 31, defined by a volute section of the housing 30, which wrap around the turbine wheel 29. Also disposed around the periphery of the turbine wheel 29 is a nozzle ring 33, which is also in fluid communication with the inlet gas passages. The nozzle ring 32 is provided with a plurality of spaced apart nozzle vanes 33, typically numbering in the region of 8 to 15. Each vane 33 has a proximal end 34 which acts as the leading edge of the vane 33 and is located toward the outer periphery of the nozzle ring 32, and an opposing distal end 35 located inwardly thereof. The exhaust gas therefore is directed from the inlet gas passage 31, flowing along the vanes 33 from their proximal to their distal ends 34,35, and in the gaps 36 between adjacent vanes 33.

The nozzle vanes 33 provide a flow restriction and therefore directly influence the flow characteristics of the exhaust gas flowing through the turbine 16 and therefore it's performance and efficiency. Typically nozzle ring vanes are used in applications where the range of operation is expected to be quite narrow, so that the vanes can be designed to match the corresponding flow conditions in the air passage(s) 31 and direct the flow onto the rotor blades of the turbine wheel 29. However it has been found, surprisingly, that the range of applicability of nozzle vanes 33 can be extended by the use of at least one tubercle (bump) 37 which in turn improves the efficiency in turbines 16 experiencing a wider range of incoming flow conditions.

To widen the optimum flow range of the nozzle vanes 33 at least one tubercle 37, or a series of spaced tubercles 37, are provided on the edge of the proximal end 34 of each vane 33. The tubercles 37 may be evenly spaced and smoothly rounded in configuration. In one embodiment the number of tubercles on each vane 33 is in the region of 10. However the number, size and shape of the tubercies 37 should be selected according to provide the best flow characteristics.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable to turbochargers used on engines such as internal combustion engines.

During use of the engine 10, a fuel, such as diesel fuel, is injected into combustion cylinders 12 and combusted. Exhaust gas produced as a result of the combustion process is directed from each combustion cylinder 12 to the exhaust manifold 15. At least a portion of the exhaust gas within the exhaust manifold 15 is directed to the turbine inlet 24, to flow through the turbine 16, thereby rotatably driving the turbine wheel 29. The spent exhaust gas is discharged from turbine 162 through turbine outlet 25. The tubercles 37 inhibit flow separation as the incidence angle of the incoming gas diverges from the design condition, thereby reducing the extent of passage blockage to the gas flow, compared to a similar nozzle vane design without tubercles 37. In this way the aerodynamic efficiency of the nozzle vanes 33, and consequently of the whole turbine stage, will be improved because the larger portion of the gas energy will be available to be converted to useful work by the turbine 16, instead of being lost through mixing processes (also known as passage loss) The turbine 16 transmits power to the compressor 17 via turbocharger shaft 23 on which they are both mounted. The compressor 17 draws in combustion gas and compresses it. The compressed combustion gas is discharged from the compressor 17 and passes along the charge air conduit 20 to the intake manifold 14.

The tubercled nozzle vanes 33 may thus he used to optimise the turbine performance in an efficient, simple construction, having no moving parts, as compared with the more complex, and therefore more expensive, adjustable vane nozzles.

Whilst the embodiments of the disclosure focus on the use of tuberoles 37 on the stationary nozzle vane 33 of a turbine 16, it is also envisaged that such tubercles 37 may also be applied to other stationary vanes, such as compressor inlet guide vanes and compressor vaned diffusers, where present on a particular turbocharger.

It is also envisaged that such tubercles 37 may also be used to improve the aerodynamic efficiency of variable (i.e. controllable) vanes in a variable geometry turbine, or variable guide vanes or variable diffuser vanes on a compressor.

Claims

-10 - CLAIMS: - 1. A turbocharger for an engine comprising a compressor and a turbine, said turbine comprising a nozzle ring provided with a plurality of vanes, said vanes having a proximal end and a distal end, the proximal end of each vane being located at an outer periphery of the nozzle ring and the distal end being located inwardly thereof, wherein the proximal end of the vanes are provided with at least one tubercls.
2. A turbocharger for an engine comprising a compressor and a turbine, said compresscr comprising a nozzle ring provided with a plurality of vanes, said vanes having a proximal end and a distal end, the proximal end of each vane being located at an outer periphery of the nozzle ring and the distal end being located inwardly thereof, wherein the proximal end of the vanes are provided with at least one tubercle.
3. A turbocharger as claimed in claim 1 or claim 2 in which the vanes are provided with a series of tubercles.
4. A turbocharger as claimed in any one of the preceding claims on which the number of vanes is in the range of 8 to 15.
5. A turbocharger as claimed in any one of the preceding claims in which the number of tubercles on each vane is 10.
6. A turbocharger as claimed in any one of the preceding claims in which the vanes are stationary.-11 -
7. A turbocharger as claimed in any one of claims 1 to 5 in which the vanes are variable.