PULSE FILTER DESIGN

A filter element includes a first filter portion extending between a first end and an opposing second end. The first filter portion includes a first cross-sectional dimension that is substantially constant along a length of the first filter portion between the first end and the second end. The filter element includes a second filter portion extending between a third end and an opposing fourth end with the third end being located adjacent the second end. The third end has a third end cross-sectional dimension that substantially matches the first cross-sectional dimension. The fourth end has a fourth end cross-sectional dimension that is smaller than the third end cross-sectional dimension.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to a filter element and, more particularly, to a filter element having an improved filtration efficiency.

2. Discussion of the Prior Art

Inlet systems for gas turbines are generally used for treating air that passes to the gas turbine. The air can be treated by filtering the air with one or more filter elements provided within the inlet system. The filtration efficiency of the inlet system is somewhat constrained by the total number of filter elements that can be accommodated within the inlet system. Additionally, factors such as the total area of filtration media, pressure drop caused by the filter elements, etc. can also affect the filtration efficiency of the inlet system. Accordingly, it would be useful to provide a filter element having a size and/or construction that allows for a greater total number of filter elements to be provided in the inlet system so as to provide an improved filtration efficiency.

BRIEF DESCRIPTION OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some example aspects of the invention. This summary is not an extensive overview of the invention. Moreover, this summary is not intended to identify critical elements of the invention nor delineate the scope of the invention. The sole purpose of the summary is to present some concepts of the invention in simplified form as a prelude to the more detailed description that is presented later.

In accordance with one aspect, the present invention provides a filter element including a first filter portion extending between a first end and an opposing second end. The first filter portion includes a first cross-sectional dimension that is substantially constant along a length of the first filter portion between the first end and the second end. The filter element includes a second filter portion extending between a third end and an opposing fourth end with the third end being located adjacent the second end. The third end has a third end cross-sectional dimension that substantially matches the first cross-sectional dimension, the fourth end having a fourth end cross-sectional dimension that is smaller than the third end cross-sectional dimension.

In accordance with another aspect, the present invention provides a filter element including a first filter portion extending along a longitudinal axis between a first end and an opposing second end. The filter element includes a second filter portion extending along the longitudinal axis between a third end and an opposing fourth end. The first filter portion and second filter portion include a plurality of sides that are substantially planar.

In accordance with another aspect, the present invention provides a filter element including a first filter portion extending along a longitudinal axis between a first end and an opposing second end. The first filter portion includes a substantially cylindrical shape. The filter element includes a second filter portion extending along the longitudinal axis between a third end and an opposing fourth end with the third end being located adjacent the second end. The second filter portion includes a substantially conical shape. The first filter portion and second filter portion include a plurality of sides that are substantially planar.

DETAILED DESCRIPTION OF THE INVENTION

Example embodiments that incorporate one or more aspects of the present invention are described and illustrated in the drawings. These illustrated examples are not intended to be a limitation on the present invention. For example, one or more aspects of the present invention can be utilized in other embodiments and even other types of devices. Moreover, certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention. Still further, in the drawings, the same reference numerals are employed for designating the same elements.

FIG. 1illustrates an example inlet system10for delivering an air flow to a device, such as a gas turbine, according to one example. An entering air flow13can be drawn from an exterior location and into the inlet system10. The entering air flow13can be filtered before exiting the inlet system10.

The inlet system10can include an inlet section14. It should be appreciated that the inlet section14is somewhat generically shown withinFIG. 1. This generic representation is intended to convey the concept that the inlet section14of the inlet system10shown inFIG. 1can represent a prior art construction or a construction in accordance with one or more aspects of the present invention as will be described below. The inlet section14can be positioned at an upstream location of the inlet system10. The inlet section14can define an open area through which the entering air flow13can enter the inlet system10. The inlet section14can include one or more hoods16. The hoods16can provide a shielding function to help protect the inlet system10from ingesting at least some materials and/or precipitation that may otherwise enter the inlet section14.

The example inlet system10can further include a filter section18positioned adjacent to, and downstream from, the inlet section14. The filter section18can be in fluid communication with the inlet section14, such that the filter section18can receive the entering air flow13from the inlet section14. The filter section18defines a chamber19that includes a substantially open area. The chamber19can be substantially hollow such that air can enter and flow through the chamber19.

The filter section18can further include one or more filter elements20positioned within the chamber19. The filter elements20are shown to extend substantially horizontally within the filter section18and can be arranged in a vertically stacked orientation (i.e., one filter element above another filter element). However, in other examples, the filter elements20can be arranged in a vertically staggered position, such that a filter element20is not positioned directly above or below an adjacent filter element. The filter elements20can be positioned adjacent a bottom wall of the filter section18at a lower location. The filter elements20can be substantially evenly spaced apart from adjacent filter elements in the vertically stacked orientation upwards towards a top wall. In further examples, the filter elements20may not be evenly spaced apart in the vertical direction, such that some filter elements are closer or farther apart from adjacent filter elements than others. Similarly, the filter elements20can be arranged to be horizontally spaced apart, such that the filter elements20can extend across the filter section18in a column-like formation. It is to be understood that the filter elements20are only generically shown, and that the inlet system10could include a greater or fewer number of filter elements than in the shown example.

The filter elements20can each be attached to a partition22that is positioned at a downstream location of the filter section18. The partition22can include a substantially vertically oriented wall that extends across the filter section18in a direction substantially perpendicular to an air flow direction. Specifically, the partition22can extend from the bottom wall towards the top wall and between opposing side walls of the filter section18. The partition22can include a substantially non-porous structure, such that air flow is reduced and/or prevented from flowing through the partition22.

The partition22includes one or more apertures23extending through the partition22. The apertures23define openings through which the air flow can exit the filter section18. As such, each of the filter elements20can be attached to surround an aperture23. The entering air flow13can therefore pass through the filter elements20prior to passing through the apertures23and exiting the filter section18. After exiting the filter section18, the air can pass through the outlet section24and through an outlet25, whereupon the air exits the outlet25as exiting air flow26.

Turning now toFIG. 2, an example filter element20is illustrated. As shown inFIG. 2, a single filter element20is depicted attached to a section of the partition22. It is to be understood that the filter element20and partition22are somewhat generically shown withinFIG. 2, and could take on a variety of constructions in accordance with one or more aspects of the present invention. For instance, the remaining filter elements can be similar and/or identical to the filter element20in the shown example or, in the alternative, could take on a number of different sizes and shapes. In some examples, the filter element20can include a plurality of filters (e.g., greater than two) joined together to form the single filter element20. In one possible example, the filter element20comprises a single, one-piece filter element.

The filter element20can include a first filter portion30. The first filter portion30can extend along a longitudinal axis32between a first end34and an opposing second end36. In an example, the first end34of the first filter portion30is attached to the partition22. The first end34can be attached to the partition22in any number of ways, including, but not limited to, adhesives, mechanical fasteners, snap fit means, or the like. The first end34of the first filter portion30can include a cross-sectional size (e.g., diameter, etc.) that substantially matches or is slightly larger than a diameter of an aperture23(shown only in phantom inFIG. 2, as the aperture23is normally not visible in such a view) through the partition22. The first filter portion30can include a first filter media38. The first filter media38can be arranged to circumferentially encircle and extend along the longitudinal axis32. The first filter media38includes any number of materials that can filter particulates from air.

The first filter portion30can have a substantially cylindrical shape, and, in particular, a circle-cylinder shape. In an example, the first filter portion30includes a circular cross-section with a substantially constant cross-sectional dimension (e.g., diameter) along the longitudinal axis32between the first end34and the second end36. The first filter portion30may include any selected dimensions (e.g., diameter and axial length). In an example, the first filter portion30includes a length of about 66 cm (˜26 inches).

The filter element20can include a second filter portion40. The second filter portion40can extend along the longitudinal axis32between a third end42and an opposing fourth end44. In an example, the third end42of the second filter portion40is positioned adjacent the second end36of the first filter portion30. In some examples, the third end42of the second filter portion40is attached to the second end36of the first filter portion30. The third end42can be positioned substantially flush with respect to the second end36, such that the first filter portion30and second filter portion40define a substantially contiguous filter element with limited/reduced openings, gaps, etc. through which air can pass through. The second filter portion40can include a truncated conical shape as one example conical shape. Also, as an example, the conical shape has a circular cross-section that varies in size along the axis (i.e., the diameter varies). In an example, the truncated conical shape of the second filter portion40can be tapered in a direction along the longitudinal axis32away from the first filter portion30. As such, the diameter decreases as the second filter portion40extends away from the first filter portion30. The second filter portion40can include a second filter media45. The second filter media45can be arranged to circumferentially encircle and extend along the longitudinal axis32. The second filter media45includes any number of materials that can filter particulates from air.

The filter element20can further include an end cap46. The end cap46can function to seal the fourth end44of the second filter portion40. The end cap46can be positioned at the fourth end44of the second filter portion40located opposite the first filter portion30. The end cap46is shown to be circular in shape, though a variety of sizes/shapes are contemplated. Accordingly, the end cap46can reduce and/or prevent the passage of air through the end of the filter element20.

Turning toFIG. 3, a side elevation view of the filter element20is illustrated. In this example, the first filter portion30can include a first cross-sectional dimension54. In an example, the first cross-sectional dimension54includes a diameter. In other examples, the first filter portion30is not limited to including a circular, cylindrical shape with a circular cross-section, and other shapes are envisioned. In an example, the first cross-sectional dimension54(e.g., diameter) of the first filter portion30is about 42 cm (˜16.5 inches). It will be appreciated, however, that the first filter portion30is not limited to this size, and, in other examples, could be larger or smaller than as illustrated.

The second filter portion40can include a third end cross-sectional dimension56. In an example, the third end cross-sectional dimension56includes a dimension (e.g., diameter) of the third end42of the second filter portion40. The second filter portion40is not limited to including a truncated, conical shape with a circular cross-section, as other shapes are envisioned. In an example, the third end cross-sectional dimension56(e.g., diameter) of the second filter portion40is about 42 cm (˜16.5 inches). It will be appreciated, however, that the second filter portion40is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. In some examples, the third end cross-sectional dimension56substantially matches the first cross-sectional dimension54.

The second filter portion40can include a fourth end cross-sectional dimension58. In an example, the fourth end cross-sectional dimension58includes a dimension (e.g., diameter) of the fourth end44of the second filter portion40. In an example, the fourth end cross-sectional dimension58of the second filter portion40is about 32 cm (˜12.75 inches). It will be appreciated, however, that the fourth end cross-sectional dimension58is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. In an example, the fourth end cross-sectional dimension58is smaller than the third end cross-sectional dimension56and the first cross-sectional dimension54.

The filter element20provides a number of benefits. In an example, the filter element20has a maximum cross-sectional size (e.g., diameter) of about 42 cm (˜16.5 inches) at the first cross-sectional dimension54and the third end cross-sectional dimension56. These cross-sectional sizes are smaller than in previous examples, such that a greater number of filter elements20can be housed within the chamber19of the filter section18, thus leading to an improved filtration efficiency of the inlet system10. In an example, the filter element20provides a larger total area of filter media (e.g., first filter media38and second filter media45) such that filtration capability of the filter element20is improved. In an example, with first filter portion30and second filter portion40each comprising a length of about 66 cm (˜26 inches), the filter element20includes a total filtration area of about 52 m2. In such an example, the first filter portion30has a total filtration area of about 34.5 m2while the second filter portion40has a total filtration area of about 17 m2. By having a maximized diameter at the junction where the first filter portion30joins the second filter portion40, pressure loss is reduced across this junction, leading to a reduced pressure drop. In addition, flow distribution and filter media utilization is increased, leading to improved filtration efficiency, longer filter life, more effective pulse cleaning, etc.

In some examples, due to these improvements in the filter element20, a fewer total number of filter elements20may be provided in the filter section18while still achieving a similar or greater filtration efficiency of the inlet system10, thus leading to a smaller sized (e.g., reduced height) filter section18. In one possible example, the filter section18may have a reduced height of about 91 cm (˜3 ft). Further, the filter elements20can exhibit a lower pressure drop within the filter section18, which leads to a longer filter life, better filtration, efficiency, etc. In some examples, the filter elements20reduces pressure drop within the filter section18by 0.2 inches water gauge.

Turning toFIG. 4, a second example filter element120is illustrated. It will be appreciated that the second filter element120is illustrated somewhat generically/schematically so as to illustrate the structure of the second filter element120. In general, the second filter element120can be attached to the partition22at an aperture (not shown) in a similar manner as described with respect to the filter element20. The second filter element120can include a filter media, such as, for example, the first filter media38and second filter media45, for filtering particulates from air.

The second filter element120can include a first filter portion130. The first filter portion130can extend along the longitudinal axis32between the first end34and the opposing second end36. The first filter portion130of the second filter element120can be attached to the partition22. In some examples, the first filter media38comprises a plurality of different first filter media38for different first sides131of the first filter portion130. For example, one of the first sides131can include a first type of the first filter media38while another of the first sides131can include a second type of the first filter media38, wherein the second type of the first filter media38is different than the first type of the first filter media38. Differences in the first filter media38for differing first sides131include, but are not limited to, the type of filter media, thickness, filtration efficiency, media area, pleating, etc.

The first filter portion130can include a generally cylindrical shape with a polygonal cross-section. For example, the first filter portion130includes a generally constant cross-sectional dimension extending along the longitudinal axis32. In this example, the first filter portion130includes one or more first sides131that are substantially planar. In the illustrated example, the first filter portion130can include eight first sides131, such that the first filter portion130defines an octagonal cross-section. As such, the presented example is an eight-sided or octagon cylinder. The first filter portion130is not limited to including eight first sides131, and in other examples, could include any number of sides, including planar sides. In an example, the first filter portion130includes a length of about 66 cm (˜26 inches).

The second filter element120can include a second filter portion140. The second filter portion140can extend along the longitudinal axis32between the third end42and the opposing fourth end44. In an example, the third end42of the second filter portion140is positioned adjacent the second end36of the first filter portion130. The third end42can be positioned substantially flush with respect to the second end36, such that the first filter portion130and second filter portion140define a substantially contiguous filter element with limited/reduced openings, gaps, etc. through which air can pass through.

The second filter portion140can include a truncated conical shape with a polygonal cross-section. For example, the second filter portion140can be tapered in a direction along the longitudinal axis32away from the first filter portion130. In some examples, the second filter portion140has a generally decreasing cross-sectional dimension extending along the longitudinal axis32from the third end42to the fourth end44. In some examples, the second filter portion140includes one or more second sides141that are substantially planar. In the illustrated example, the second filter portion140can include eight second sides141, such that the second filter portion140defines an octagonal cross-section. The second filter portion140is not limited to including eight second sides141, and in other examples, could include any number of sides, including planar sides. In an example, the second filter portion140includes a length of about 66 cm (˜26 inches).

In some examples, the second filter media45comprises a plurality of different second filter media45for different second sides141of the second filter portion140. For example, one of the second sides141can include a first type of the second filter media45while another of the second sides141can include a second type of the second filter media45, wherein the second type of the second filter media45is different than the first type of the second filter media45. Differences in the second filter media45for differing second sides141include, but are not limited to, the type of filter media, thickness, filtration efficiency, media area, pleating, etc.

Turning toFIG. 5, a side elevation view of the second filter element120is illustrated. In this example, the first filter portion130includes a first cross-sectional dimension154. In an example, the first cross-sectional dimension154of the first filter portion130is about 42 cm (˜16.5 inches). It will be appreciated, however, that the first filter portion130is not limited to this size, and, in other examples, could be larger or smaller than as illustrated.

The second filter portion140can include a third end cross-sectional dimension156. The third end cross-sectional dimension156includes a dimension of the third end42of the second filter portion140. In an example, the third end cross-sectional dimension156of the second filter portion140is about 42 cm (˜16.5 inches). It will be appreciated, however, that the second filter portion140is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. In some examples, the third end cross-sectional dimension156substantially matches the first cross-sectional dimension154.

The second filter portion140can include a fourth end cross-sectional dimension158. The fourth end cross-sectional dimension158includes a dimension of the fourth end44of the second filter portion140. In an example, the fourth end cross-sectional dimension158of the second filter portion140is about 32 cm (˜12.75 inches). It will be appreciated, however, that the fourth end cross-sectional dimension158is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. In an example, the fourth end cross-sectional dimension158is smaller than the third end cross-sectional dimension156and the first cross-sectional dimension154.

Turning toFIG. 6, a third example filter element220is illustrated. It will be appreciated that the third filter element220is illustrated somewhat generically/schematically so as to illustrate the structure of the third filter element220. In general, the third filter element220can be attached to the partition22in a similar manner as described with respect to the filter element20and the second filter element120. The third filter element220can include a filter media, such as, for example, the first filter media38and second filter media45, for filtering particulates from air.

The third filter element220can include a first filter portion230. The first filter portion230can extend along the longitudinal axis32between the first end34and the opposing second end36. The first filter portion230of the third filter element220can be attached to the partition22.

The first filter portion230can include a truncated conical shape with a polygonal cross-section. For example, the first filter portion230can be tapered in a direction along the longitudinal axis32away from the partition22. In some examples, the first filter portion230has a generally decreasing cross-sectional dimension extending along the longitudinal axis32from the first end to the second end36. In some examples, the first filter portion230includes one or more first sides231that are planar. In the illustrated example, the first filter portion230can include eight first sides231, such that the first filter portion230defines an octagonal cross-section. The first filter portion230is not limited to including eight first sides231, and in other examples, could include any number of sides, including planar sides. In an example, the first filter portion230includes a length of about 66 cm (˜26 inches).

The third filter element220can include a second filter portion240. The second filter portion240can extend along the longitudinal axis32between the third end42and the opposing fourth end44. In an example, the third end42of the second filter portion140is positioned adjacent and in attachment with the second end36of the first filter portion230. The third end42can be positioned substantially flush with respect to the second end36, such that the first filter portion230and second filter portion240define a substantially contiguous filter element with limited/reduced openings, gaps, etc. through which air can pass through.

The second filter portion240can include a substantially cylindrical shape with a polygonal cross-section. For example, the second filter portion240includes a generally constant cross-sectional dimension extending along the longitudinal axis32. In this example, the second filter portion240includes one or more second sides241that are planar. In the illustrated example, the second filter portion240can include eight second sides241, such that the second filter portion240defines an octagonal cross-section. The second filter portion240is not limited to including eight second sides241, and in other examples, could include any number of sides, including planar sides. In an example, the second filter portion240includes a length of about 66 cm (˜26 inches).

Turning toFIG. 7, a side elevation view of the third filter element220is illustrated. In this example, the first filter portion230includes a first cross-sectional dimension254. In this example, the first cross-sectional dimension254represents a cross-sectional dimension at the first end34of the first filter portion230. In an example, the first cross-sectional dimension254at the first end34of the first filter portion230is about 42 cm (˜16.5 inches). It will be appreciated, however, that the first filter portion230is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. In an example, a cross-sectional dimension at the second end36of the first filter portion34is about 32 cm (˜12.75 inches).

The second filter portion240can include a second cross-sectional dimension258. The second cross-sectional dimension258includes a dimension of the second filter portion240at nearly any location along a length of the second filter portion240(e.g., at the third end42, at the fourth end44, etc.). In an example, the second cross-sectional dimension258of the second filter portion240is about 32 cm (˜12.75 inches). In the illustrated example, the second cross-sectional dimension258substantially matches a cross-sectional dimension of the second end36of the first filter portion230. It will be appreciated, however, that the second filter portion240is not limited to this size, and, in other examples, could be larger or smaller than as illustrated. The second cross-sectional dimension258can be less than the first cross-sectional dimension254.

Turning now toFIG. 8, an end view of a fourth example filter element320is illustrated. It will be appreciated that the fourth filter element is illustrated somewhat generically/schematically for illustrative purposes. In an example, the fourth filter element320can include at least some structures similar to the filter elements20,120,220. For example, the fourth filter element320can be attached to the partition22and can include a filter media (e.g., first filter media38and second filter media45). In the illustrated example, the fourth filter element320can include a hexagonal cross-sectional shape. The fourth filter element320can include six sides331that are planar. In an example, similar to the second filter element120ofFIG. 4, the fourth filter element320can include a first filter portion that is substantially cylindrical and a second filter portion that is substantially conical. In another example, similar to the third filter element220ofFIG. 6, the fourth filter element320can include a first filter portion that is substantially conical and a second filter portion that is substantially cylindrical.

As illustrated inFIGS. 4 to 8, the filter elements120,220,320having one or more substantially planar sides provide a number of benefits. In one example, the filter elements120,220,320can include a staggered arrangement within the chamber19of the filter section18. For example, the substantially planar sides (e.g., first sides131,231,331and/or second sides141,241,331) of one filter element120,220,320can be positioned adjacent and in proximity to substantially planar sides (e.g., first sides131,231,331and/or second sides141,241,331) of an adjacent filter element120,220,320. In some examples, adjacent substantially planar sides of adjacent filter elements can extend generally parallel with respect to each other, with a small opening, gap, space, etc. therebetween. This staggered arrangement of the filter elements120,220,320can allow for a larger number of the filter elements120,220,320to be housed within the filter section18, thus leading to an increased filtration capacity of the inlet system10.

As illustrated inFIGS. 2 to 8, the filter elements20,120,220,320each include the filter media38,45comprising a plurality of different media configurations. For example, in some examples, the filter media38,45is arranged to have the substantially cylindrical shape (e.g., as illustrated inFIG. 2). In other examples, the filter media38,45is arranged to include one or more planar sides (e.g., sides131,141,231,241,331, etc.). In these examples, the filter elements20,120,220,320provide a number of benefits, including, but not limited to, better flow distribution and filter media utilization, improved filtration efficiency, longer filter life, more effective pulse cleaning, etc.

Turning now toFIG. 9, a sectional view of a portion of one of the second filter element120, third filter element220, or fourth filter element320is illustrated. In particular, a side of one of the second filter element120, third filter element220, or fourth filter element320is illustrated. It will be appreciated that the illustrated side is generally planar, and can include portions of any one of the illustrated sides131,141,231,241,331.

The filter elements,120,220,320can include a filter media400. The filter media400includes any number of different materials. For example, the filter media400can include a variety of filtering materials that function to remove particulates from air that passes through the filter media400. In an example, the filter media400can include polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE), for example.

In some examples, the filter media400can be supported by a first support device402. In an example, the first support device402can extend concentrically about the filter media400. The first support device402can have a larger diameter than the filter media400. The first support device402can define an outermost surface of the filter elements120,220,320. In an example, the first support device402can form a generally linear side so as to match the polygonal shape of the filter elements120,220,320. It will be appreciated that the first support device402may not be present in all examples of the filter elements120,220,320. Rather, in some examples, the filter elements120,220,320may not be provided with the first support device402.

The filter media400can be supported by a second support device404. The second support device404defines an innermost surface of the filter elements120,220,320. The second support device404can be spaced apart inwardly from the first support device402to define an opening, chamber, etc. extending between the first support device402and the second support device404. In an example, the second support device404can extend generally linearly to extend generally parallel to the first support device402.

It will be appreciated that the second support device404may not be present in all examples of the filter elements120,220,320. Rather, in some examples, the filter elements120,220,320may not be provided with the second support device404. In some possible examples, either or both of the first support device402or second support device404may be replaced by a scrim, adhesive, adhesive impregnated string, other support device, etc., alone or in combination. Likewise, in some examples, the filter elements120,220,320may not include both of the first support device402and second support device404. Rather, the filter elements120,220,320may instead include one of the first support device402or the second support device404.

The filter media400defines an inner surface410and an outer surface412. The inner surface410can at least partially be in contact with and/or supported by the second support device404. The outer surface412can at least partially be in contact with and/or supported by the first support device402. In some examples, the filter media400is arranged so as to include a plurality of pleats420that extend in a substantially zig-zag pattern toward and away from the first support device402and the second support device404.

By providing the filter elements120,220,320with one or more substantially planar sides131,141,231,241,331, spacing between the pleats is maintained substantially constant. For example, an outer separating distance430is a distance separating adjacent outer pleats420supported by the first support device402. An inner separating distance440is a distance separating adjacent inner pleats420supported by the second support device404. In an example, the outer separating distance430can substantially match the inner separating distance440due, at least in part, to the pleats420forming substantially planar sides131,141,231,241,331. As such, bunching of the pleats420at an inner location, as is known to occur in rounded/curved filter elements, is reduced. In addition to bunching (e.g., an irregular grouping of pleats), tightness of pleat exit compared to pleat entry is also reduced. As a result, in some examples, pressure loss is reduced while filtration efficiency and filter life are increased through better media utilization and improved pulse cleaning.